void
mpfr_urandomb (mpfr_ptr rop, gmp_randstate_t rstate)
{
mp_ptr rp;
mp_size_t nlimbs;
mp_exp_t exp;
unsigned long cnt, nbits;
MPFR_CLEAR_FLAGS(rop);
rp = MPFR_MANT(rop);
nbits = MPFR_PREC(rop);
nlimbs = (nbits + BITS_PER_MP_LIMB - 1) / BITS_PER_MP_LIMB;
_gmp_rand (rp, rstate, nbits);
/* If nbits isn't a multiple of BITS_PER_MP_LIMB, shift up. */
if (nlimbs != 0)
{
if (nbits % BITS_PER_MP_LIMB != 0)
mpn_lshift (rp, rp, nlimbs,
BITS_PER_MP_LIMB - nbits % BITS_PER_MP_LIMB);
}
exp = 0;
while (nlimbs != 0 && rp[nlimbs - 1] == 0)
{
nlimbs--;
exp--;
}
if (nlimbs != 0) /* otherwise value is zero */
{
count_leading_zeros (cnt, rp[nlimbs - 1]);
if (cnt) mpn_lshift (rp, rp, nlimbs, cnt);
exp -= cnt;
cnt = nlimbs*BITS_PER_MP_LIMB - nbits;
/* cnt is the number of non significant bits in the low limb */
rp[0] &= ~((MP_LIMB_T_ONE << cnt) - 1);
}
MPFR_EXP (rop) = exp;
}
int
mpfr_cmp_d (mpfr_srcptr b, double d)
{
mpfr_t tmp;
int res;
mp_limb_t tmp_man[MPFR_LIMBS_PER_DOUBLE];
MPFR_SAVE_EXPO_DECL (expo);
MPFR_SAVE_EXPO_MARK (expo);
MPFR_TMP_INIT1(tmp_man, tmp, IEEE_DBL_MANT_DIG);
res = mpfr_set_d (tmp, d, MPFR_RNDN);
MPFR_ASSERTD (res == 0);
MPFR_CLEAR_FLAGS ();
res = mpfr_cmp (b, tmp);
MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, __gmpfr_flags);
MPFR_SAVE_EXPO_FREE (expo);
return res;
}
int
mpfr_overflow (mpfr_ptr x, mp_rnd_t rnd_mode, int sign)
{
int inex;
MPFR_ASSERT_SIGN(sign);
MPFR_CLEAR_FLAGS(x);
if (rnd_mode == GMP_RNDN
|| MPFR_IS_RNDUTEST_OR_RNDDNOTTEST(rnd_mode, sign > 0))
{
MPFR_SET_INF(x);
inex = 1;
}
else
{
mpfr_setmax (x, __gmpfr_emax);
inex = -1;
}
MPFR_SET_SIGN(x,sign);
__gmpfr_flags |= MPFR_FLAGS_INEXACT | MPFR_FLAGS_OVERFLOW;
return sign > 0 ? inex : -inex;
}
int
mpfr_exp2 (mpfr_ptr y, mpfr_srcptr x, mpfr_rnd_t rnd_mode)
{
int inexact;
long xint;
mpfr_t xfrac;
MPFR_SAVE_EXPO_DECL (expo);
MPFR_LOG_FUNC
(("x[%Pu]=%.*Rg rnd=%d", mpfr_get_prec(x), mpfr_log_prec, x, rnd_mode),
("y[%Pu]=%.*Rg inexact=%d", mpfr_get_prec(y), mpfr_log_prec, y,
inexact));
if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
{
if (MPFR_IS_NAN (x))
{
MPFR_SET_NAN (y);
MPFR_RET_NAN;
}
else if (MPFR_IS_INF (x))
{
if (MPFR_IS_POS (x))
MPFR_SET_INF (y);
else
MPFR_SET_ZERO (y);
MPFR_SET_POS (y);
MPFR_RET (0);
}
else /* 2^0 = 1 */
{
MPFR_ASSERTD (MPFR_IS_ZERO(x));
return mpfr_set_ui (y, 1, rnd_mode);
}
}
/* since the smallest representable non-zero float is 1/2*2^__gmpfr_emin,
if x < __gmpfr_emin - 1, the result is either 1/2*2^__gmpfr_emin or 0 */
MPFR_ASSERTN (MPFR_EMIN_MIN >= LONG_MIN + 2);
if (MPFR_UNLIKELY (mpfr_cmp_si (x, __gmpfr_emin - 1) < 0))
{
mpfr_rnd_t rnd2 = rnd_mode;
/* in round to nearest mode, round to zero when x <= __gmpfr_emin-2 */
if (rnd_mode == MPFR_RNDN &&
mpfr_cmp_si_2exp (x, __gmpfr_emin - 2, 0) <= 0)
rnd2 = MPFR_RNDZ;
return mpfr_underflow (y, rnd2, 1);
}
MPFR_ASSERTN (MPFR_EMAX_MAX <= LONG_MAX);
if (MPFR_UNLIKELY (mpfr_cmp_si (x, __gmpfr_emax) >= 0))
return mpfr_overflow (y, rnd_mode, 1);
/* We now know that emin - 1 <= x < emax. */
MPFR_SAVE_EXPO_MARK (expo);
/* 2^x = 1 + x*log(2) + O(x^2) for x near zero, and for |x| <= 1 we have
|2^x - 1| <= x < 2^EXP(x). If x > 0 we must round away from 0 (dir=1);
if x < 0 we must round toward 0 (dir=0). */
MPFR_SMALL_INPUT_AFTER_SAVE_EXPO (y, __gmpfr_one, - MPFR_GET_EXP (x), 0,
MPFR_IS_POS (x), rnd_mode, expo, {});
xint = mpfr_get_si (x, MPFR_RNDZ);
mpfr_init2 (xfrac, MPFR_PREC (x));
mpfr_sub_si (xfrac, x, xint, MPFR_RNDN); /* exact */
if (MPFR_IS_ZERO (xfrac))
{
mpfr_set_ui (y, 1, MPFR_RNDN);
inexact = 0;
}
else
{
/* Declaration of the intermediary variable */
mpfr_t t;
/* Declaration of the size variable */
mpfr_prec_t Ny = MPFR_PREC(y); /* target precision */
mpfr_prec_t Nt; /* working precision */
mpfr_exp_t err; /* error */
MPFR_ZIV_DECL (loop);
/* compute the precision of intermediary variable */
/* the optimal number of bits : see algorithms.tex */
Nt = Ny + 5 + MPFR_INT_CEIL_LOG2 (Ny);
/* initialize of intermediary variable */
mpfr_init2 (t, Nt);
/* First computation */
MPFR_ZIV_INIT (loop, Nt);
for (;;)
{
/* compute exp(x*ln(2))*/
mpfr_const_log2 (t, MPFR_RNDU); /* ln(2) */
mpfr_mul (t, xfrac, t, MPFR_RNDU); /* xfrac * ln(2) */
err = Nt - (MPFR_GET_EXP (t) + 2); /* Estimate of the error */
mpfr_exp (t, t, MPFR_RNDN); /* exp(xfrac * ln(2)) */
if (MPFR_LIKELY (MPFR_CAN_ROUND (t, err, Ny, rnd_mode)))
break;
/* Actualisation of the precision */
MPFR_ZIV_NEXT (loop, Nt);
mpfr_set_prec (t, Nt);
}
MPFR_ZIV_FREE (loop);
inexact = mpfr_set (y, t, rnd_mode);
mpfr_clear (t);
}
mpfr_clear (xfrac);
MPFR_CLEAR_FLAGS ();
mpfr_mul_2si (y, y, xint, MPFR_RNDN); /* exact or overflow */
/* Note: We can have an overflow only when t was rounded up to 2. */
MPFR_ASSERTD (MPFR_IS_PURE_FP (y) || inexact > 0);
MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, __gmpfr_flags);
MPFR_SAVE_EXPO_FREE (expo);
return mpfr_check_range (y, inexact, rnd_mode);
}
int
mpfr_div (mpfr_ptr q, mpfr_srcptr u, mpfr_srcptr v, mp_rnd_t rnd_mode)
{
mp_srcptr up, vp, bp;
mp_size_t usize, vsize;
mp_ptr ap, qp, rp;
mp_size_t asize, bsize, qsize, rsize;
mp_exp_t qexp;
mp_size_t err, k;
mp_limb_t tonearest;
int inex, sh, can_round = 0, sign_quotient;
unsigned int cc = 0, rw;
TMP_DECL (marker);
/**************************************************************************
* *
* This part of the code deals with special cases *
* *
**************************************************************************/
if (MPFR_ARE_SINGULAR(u,v))
{
if (MPFR_IS_NAN(u) || MPFR_IS_NAN(v))
{
MPFR_SET_NAN(q);
MPFR_RET_NAN;
}
sign_quotient = MPFR_MULT_SIGN( MPFR_SIGN(u) , MPFR_SIGN(v) );
MPFR_SET_SIGN(q, sign_quotient);
if (MPFR_IS_INF(u))
{
if (MPFR_IS_INF(v))
{
MPFR_SET_NAN(q);
MPFR_RET_NAN;
}
else
{
MPFR_SET_INF(q);
MPFR_RET(0);
}
}
else if (MPFR_IS_INF(v))
{
MPFR_SET_ZERO(q);
MPFR_RET(0);
}
else if (MPFR_IS_ZERO(v))
{
if (MPFR_IS_ZERO(u))
{
MPFR_SET_NAN(q);
MPFR_RET_NAN;
}
else
{
MPFR_SET_INF(q);
MPFR_RET(0);
}
}
else
{
MPFR_ASSERTD(MPFR_IS_ZERO(u));
MPFR_SET_ZERO(q);
MPFR_RET(0);
}
}
MPFR_CLEAR_FLAGS(q);
/**************************************************************************
* *
* End of the part concerning special values. *
* *
**************************************************************************/
sign_quotient = MPFR_MULT_SIGN( MPFR_SIGN(u) , MPFR_SIGN(v) );
up = MPFR_MANT(u);
vp = MPFR_MANT(v);
MPFR_SET_SIGN(q, sign_quotient);
TMP_MARK (marker);
usize = MPFR_LIMB_SIZE(u);
vsize = MPFR_LIMB_SIZE(v);
/**************************************************************************
* *
* First try to use only part of u, v. If this is not sufficient, *
* use the full u and v, to avoid long computations eg. in the case *
* u = v. *
* *
**************************************************************************/
/* The dividend is a, length asize. The divisor is b, length bsize. */
qsize = (MPFR_PREC(q) + 3) / BITS_PER_MP_LIMB + 1;
/* in case PREC(q)=PREC(v), then vsize=qsize with probability 1-4/b
where b is the number of bits per limb */
if (MPFR_LIKELY(vsize <= qsize))
{
bsize = vsize;
bp = vp;
}
else /* qsize < vsize: take only the qsize high limbs of the divisor */
{
bsize = qsize;
bp = (mp_srcptr) vp + (vsize - qsize);
}
/* we have {bp, bsize} * (1 + errb) = (true divisor)
with 0 <= errb < 2^(-qsize*BITS_PER_MP_LIMB+1) */
asize = bsize + qsize;
ap = (mp_ptr) TMP_ALLOC (asize * BYTES_PER_MP_LIMB);
/* if all arguments have same precision, then asize will be about 2*usize */
if (MPFR_LIKELY(asize > usize))
{
/* copy u into the high limbs of {ap, asize}, and pad with zeroes */
/* FIXME: could we copy only the qsize high limbs of the dividend? */
MPN_COPY (ap + asize - usize, up, usize);
MPN_ZERO (ap, asize - usize);
}
else /* truncate the high asize limbs of u into {ap, asize} */
MPN_COPY (ap, up + usize - asize, asize);
/* we have {ap, asize} = (true dividend) * (1 - erra)
with 0 <= erra < 2^(-asize*BITS_PER_MP_LIMB).
This {ap, asize} / {bp, bsize} =
(true dividend) / (true divisor) * (1 - erra) (1 + errb) */
/* Allocate limbs for quotient and remainder. */
qp = (mp_ptr) TMP_ALLOC ((qsize + 1) * BYTES_PER_MP_LIMB);
rp = (mp_ptr) TMP_ALLOC (bsize * BYTES_PER_MP_LIMB);
rsize = bsize;
mpn_tdiv_qr (qp, rp, 0, ap, asize, bp, bsize);
sh = - (int) qp[qsize];
/* since u and v are normalized, sh is 0 or -1 */
/* we have {qp, qsize + 1} = {ap, asize} / {bp, bsize} (1 - errq)
with 0 <= errq < 2^(-qsize*BITS_PER_MP_LIMB+1+sh)
thus {qp, qsize + 1} =
(true dividend) / (true divisor) * (1 - erra) (1 + errb) (1 - errq).
In fact, since the truncated dividend and {rp, bsize} do not overlap,
we have: {qp, qsize + 1} =
(true dividend) / (true divisor) * (1 - erra') (1 + errb)
where 0 <= erra' < 2^(-qsize*BITS_PER_MP_LIMB+sh) */
/* Estimate number of correct bits. */
err = qsize * BITS_PER_MP_LIMB;
/* We want to check if rounding is possible, but without normalizing
because we might have to divide again if rounding is impossible, or
if the result might be exact. We have however to mimic normalization */
/*
To detect asap if the result is inexact, so as to avoid doing the
division completely, we perform the following check :
- if rnd_mode != GMP_RNDN, and the result is exact, we are unable
to round simultaneously to zero and to infinity ;
- if rnd_mode == GMP_RNDN, and if we can round to zero with one extra
bit of precision, we can decide rounding. Hence in that case, check
as in the case of GMP_RNDN, with one extra bit. Note that in the case
of close to even rounding we shall do the division completely, but
this is necessary anyway : we need to know whether this is really
even rounding or not.
*/
if (MPFR_UNLIKELY(asize < usize || bsize < vsize))
{
{
mp_rnd_t rnd_mode1, rnd_mode2;
mp_exp_t tmp_exp;
mp_prec_t tmp_prec;
if (bsize < vsize)
err -= 2; /* divisor is truncated */
#if 0 /* commented this out since the truncation of the dividend is already
taken into account in {rp, bsize}, which does not overlap with the
neglected part of the dividend */
else if (asize < usize)
err --; /* dividend is truncated */
#endif
if (MPFR_LIKELY(rnd_mode == GMP_RNDN))
{
rnd_mode1 = GMP_RNDZ;
rnd_mode2 = MPFR_IS_POS_SIGN(sign_quotient) ? GMP_RNDU : GMP_RNDD;
sh++;
}
else
{
rnd_mode1 = rnd_mode;
switch (rnd_mode)
{
case GMP_RNDU:
rnd_mode2 = GMP_RNDD; break;
case GMP_RNDD:
rnd_mode2 = GMP_RNDU; break;
default:
rnd_mode2 = MPFR_IS_POS_SIGN(sign_quotient) ?
GMP_RNDU : GMP_RNDD;
break;
}
}
tmp_exp = err + sh + BITS_PER_MP_LIMB;
tmp_prec = MPFR_PREC(q) + sh + BITS_PER_MP_LIMB;
can_round =
mpfr_can_round_raw (qp, qsize + 1, sign_quotient, tmp_exp,
GMP_RNDN, rnd_mode1, tmp_prec)
& mpfr_can_round_raw (qp, qsize + 1, sign_quotient, tmp_exp,
GMP_RNDN, rnd_mode2, tmp_prec);
/* restore original value of sh, i.e. sh = - qp[qsize] */
sh -= (rnd_mode == GMP_RNDN);
}
int
mpfr_pow_si (mpfr_ptr y, mpfr_srcptr x, long int n, mp_rnd_t rnd)
{
if (n >= 0)
return mpfr_pow_ui (y, x, n, rnd);
else
{
if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
{
if (MPFR_IS_NAN (x))
{
MPFR_SET_NAN (y);
MPFR_RET_NAN;
}
else if (MPFR_IS_INF (x))
{
MPFR_SET_ZERO (y);
if (MPFR_IS_POS (x) || ((unsigned) n & 1) == 0)
MPFR_SET_POS (y);
else
MPFR_SET_NEG (y);
MPFR_RET (0);
}
else /* x is zero */
{
MPFR_ASSERTD (MPFR_IS_ZERO (x));
MPFR_SET_INF(y);
if (MPFR_IS_POS (x) || ((unsigned) n & 1) == 0)
MPFR_SET_POS (y);
else
MPFR_SET_NEG (y);
MPFR_RET(0);
}
}
MPFR_CLEAR_FLAGS (y);
/* detect exact powers: x^(-n) is exact iff x is a power of 2 */
if (mpfr_cmp_si_2exp (x, MPFR_SIGN(x), MPFR_EXP(x) - 1) == 0)
{
mp_exp_t expx = MPFR_EXP (x) - 1, expy;
MPFR_ASSERTD (n < 0);
/* Warning: n * expx may overflow!
* Some systems (apparently alpha-freebsd) abort with
* LONG_MIN / 1, and LONG_MIN / -1 is undefined.
* Proof of the overflow checking. The expressions below are
* assumed to be on the rational numbers, but the word "overflow"
* still has its own meaning in the C context. / still denotes
* the integer (truncated) division, and // denotes the exact
* division.
* - First, (__gmpfr_emin - 1) / n and (__gmpfr_emax - 1) / n
* cannot overflow due to the constraints on the exponents of
* MPFR numbers.
* - If n = -1, then n * expx = - expx, which is representable
* because of the constraints on the exponents of MPFR numbers.
* - If expx = 0, then n * expx = 0, which is representable.
* - If n < -1 and expx > 0:
* + If expx > (__gmpfr_emin - 1) / n, then
* expx >= (__gmpfr_emin - 1) / n + 1
* > (__gmpfr_emin - 1) // n,
* and
* n * expx < __gmpfr_emin - 1,
* i.e.
* n * expx <= __gmpfr_emin - 2.
* This corresponds to an underflow, with a null result in
* the rounding-to-nearest mode.
* + If expx <= (__gmpfr_emin - 1) / n, then n * expx cannot
* overflow since 0 < expx <= (__gmpfr_emin - 1) / n and
* 0 > n * expx >= n * ((__gmpfr_emin - 1) / n)
* >= __gmpfr_emin - 1.
* - If n < -1 and expx < 0:
* + If expx < (__gmpfr_emax - 1) / n, then
* expx <= (__gmpfr_emax - 1) / n - 1
* < (__gmpfr_emax - 1) // n,
* and
* n * expx > __gmpfr_emax - 1,
* i.e.
* n * expx >= __gmpfr_emax.
* This corresponds to an overflow (2^(n * expx) has an
* exponent > __gmpfr_emax).
* + If expx >= (__gmpfr_emax - 1) / n, then n * expx cannot
* overflow since 0 > expx >= (__gmpfr_emax - 1) / n and
* 0 < n * expx <= n * ((__gmpfr_emax - 1) / n)
* <= __gmpfr_emax - 1.
* Note: one could use expx bounds based on MPFR_EXP_MIN and
* MPFR_EXP_MAX instead of __gmpfr_emin and __gmpfr_emax. The
* current bounds do not lead to noticeably slower code and
* allow us to avoid a bug in Sun's compiler for Solaris/x86
* (when optimizations are enabled).
*/
expy =
n != -1 && expx > 0 && expx > (__gmpfr_emin - 1) / n ?
MPFR_EMIN_MIN - 2 /* Underflow */ :
n != -1 && expx < 0 && expx < (__gmpfr_emax - 1) / n ?
MPFR_EMAX_MAX /* Overflow */ : n * expx;
return mpfr_set_si_2exp (y, n % 2 ? MPFR_INT_SIGN (x) : 1,
expy, rnd);
}
/* General case */
{
/* Declaration of the intermediary variable */
mpfr_t t;
/* Declaration of the size variable */
mp_prec_t Ny = MPFR_PREC (y); /* target precision */
mp_prec_t Nt; /* working precision */
mp_exp_t err; /* error */
int inexact;
unsigned long abs_n;
MPFR_SAVE_EXPO_DECL (expo);
MPFR_ZIV_DECL (loop);
abs_n = - (unsigned long) n;
/* compute the precision of intermediary variable */
/* the optimal number of bits : see algorithms.tex */
Nt = Ny + 3 + MPFR_INT_CEIL_LOG2 (Ny);
MPFR_SAVE_EXPO_MARK (expo);
/* initialise of intermediary variable */
mpfr_init2 (t, Nt);
MPFR_ZIV_INIT (loop, Nt);
for (;;)
{
/* compute 1/(x^n), with n > 0 */
mpfr_pow_ui (t, x, abs_n, GMP_RNDN);
mpfr_ui_div (t, 1, t, GMP_RNDN);
/* FIXME: old code improved, but I think this is still incorrect. */
if (MPFR_UNLIKELY (MPFR_IS_ZERO (t)))
{
MPFR_ZIV_FREE (loop);
mpfr_clear (t);
MPFR_SAVE_EXPO_FREE (expo);
return mpfr_underflow (y, rnd == GMP_RNDN ? GMP_RNDZ : rnd,
abs_n & 1 ? MPFR_SIGN (x) :
MPFR_SIGN_POS);
}
if (MPFR_UNLIKELY (MPFR_IS_INF (t)))
{
MPFR_ZIV_FREE (loop);
mpfr_clear (t);
MPFR_SAVE_EXPO_FREE (expo);
return mpfr_overflow (y, rnd, abs_n & 1 ? MPFR_SIGN (x) :
MPFR_SIGN_POS);
}
/* error estimate -- see pow function in algorithms.ps */
err = Nt - 3;
if (MPFR_LIKELY (MPFR_CAN_ROUND (t, err, Ny, rnd)))
break;
/* actualisation of the precision */
Nt += BITS_PER_MP_LIMB;
mpfr_set_prec (t, Nt);
}
MPFR_ZIV_FREE (loop);
inexact = mpfr_set (y, t, rnd);
mpfr_clear (t);
MPFR_SAVE_EXPO_FREE (expo);
return mpfr_check_range (y, inexact, rnd);
}
}
}
/* The computation of z = pow(x,y) is done by
z = exp(y * log(x)) = x^y
For the special cases, see Section F.9.4.4 of the C standard:
_ pow(±0, y) = ±inf for y an odd integer < 0.
_ pow(±0, y) = +inf for y < 0 and not an odd integer.
_ pow(±0, y) = ±0 for y an odd integer > 0.
_ pow(±0, y) = +0 for y > 0 and not an odd integer.
_ pow(-1, ±inf) = 1.
_ pow(+1, y) = 1 for any y, even a NaN.
_ pow(x, ±0) = 1 for any x, even a NaN.
_ pow(x, y) = NaN for finite x < 0 and finite non-integer y.
_ pow(x, -inf) = +inf for |x| < 1.
_ pow(x, -inf) = +0 for |x| > 1.
_ pow(x, +inf) = +0 for |x| < 1.
_ pow(x, +inf) = +inf for |x| > 1.
_ pow(-inf, y) = -0 for y an odd integer < 0.
_ pow(-inf, y) = +0 for y < 0 and not an odd integer.
_ pow(-inf, y) = -inf for y an odd integer > 0.
_ pow(-inf, y) = +inf for y > 0 and not an odd integer.
_ pow(+inf, y) = +0 for y < 0.
_ pow(+inf, y) = +inf for y > 0. */
int
mpfr_pow (mpfr_ptr z, mpfr_srcptr x, mpfr_srcptr y, mpfr_rnd_t rnd_mode)
{
int inexact;
int cmp_x_1;
int y_is_integer;
MPFR_SAVE_EXPO_DECL (expo);
MPFR_LOG_FUNC
(("x[%Pu]=%.*Rg y[%Pu]=%.*Rg rnd=%d",
mpfr_get_prec (x), mpfr_log_prec, x,
mpfr_get_prec (y), mpfr_log_prec, y, rnd_mode),
("z[%Pu]=%.*Rg inexact=%d",
mpfr_get_prec (z), mpfr_log_prec, z, inexact));
if (MPFR_ARE_SINGULAR (x, y))
{
/* pow(x, 0) returns 1 for any x, even a NaN. */
if (MPFR_UNLIKELY (MPFR_IS_ZERO (y)))
return mpfr_set_ui (z, 1, rnd_mode);
else if (MPFR_IS_NAN (x))
{
MPFR_SET_NAN (z);
MPFR_RET_NAN;
}
else if (MPFR_IS_NAN (y))
{
/* pow(+1, NaN) returns 1. */
if (mpfr_cmp_ui (x, 1) == 0)
return mpfr_set_ui (z, 1, rnd_mode);
MPFR_SET_NAN (z);
MPFR_RET_NAN;
}
else if (MPFR_IS_INF (y))
{
if (MPFR_IS_INF (x))
{
if (MPFR_IS_POS (y))
MPFR_SET_INF (z);
else
MPFR_SET_ZERO (z);
MPFR_SET_POS (z);
MPFR_RET (0);
}
else
{
int cmp;
cmp = mpfr_cmpabs (x, __gmpfr_one) * MPFR_INT_SIGN (y);
MPFR_SET_POS (z);
if (cmp > 0)
{
/* Return +inf. */
MPFR_SET_INF (z);
MPFR_RET (0);
}
else if (cmp < 0)
{
/* Return +0. */
MPFR_SET_ZERO (z);
MPFR_RET (0);
}
else
{
/* Return 1. */
return mpfr_set_ui (z, 1, rnd_mode);
}
}
}
else if (MPFR_IS_INF (x))
{
int negative;
/* Determine the sign now, in case y and z are the same object */
negative = MPFR_IS_NEG (x) && is_odd (y);
if (MPFR_IS_POS (y))
MPFR_SET_INF (z);
else
MPFR_SET_ZERO (z);
if (negative)
MPFR_SET_NEG (z);
else
MPFR_SET_POS (z);
MPFR_RET (0);
}
else
{
int negative;
MPFR_ASSERTD (MPFR_IS_ZERO (x));
/* Determine the sign now, in case y and z are the same object */
negative = MPFR_IS_NEG(x) && is_odd (y);
if (MPFR_IS_NEG (y))
{
MPFR_ASSERTD (! MPFR_IS_INF (y));
MPFR_SET_INF (z);
mpfr_set_divby0 ();
}
else
MPFR_SET_ZERO (z);
if (negative)
MPFR_SET_NEG (z);
else
MPFR_SET_POS (z);
MPFR_RET (0);
}
}
/* x^y for x < 0 and y not an integer is not defined */
y_is_integer = mpfr_integer_p (y);
if (MPFR_IS_NEG (x) && ! y_is_integer)
{
MPFR_SET_NAN (z);
MPFR_RET_NAN;
}
/* now the result cannot be NaN:
(1) either x > 0
(2) or x < 0 and y is an integer */
cmp_x_1 = mpfr_cmpabs (x, __gmpfr_one);
if (cmp_x_1 == 0)
return mpfr_set_si (z, MPFR_IS_NEG (x) && is_odd (y) ? -1 : 1, rnd_mode);
/* now we have:
(1) either x > 0
(2) or x < 0 and y is an integer
and in addition |x| <> 1.
*/
/* detect overflow: an overflow is possible if
(a) |x| > 1 and y > 0
(b) |x| < 1 and y < 0.
FIXME: this assumes 1 is always representable.
FIXME2: maybe we can test overflow and underflow simultaneously.
The idea is the following: first compute an approximation to
y * log2|x|, using rounding to nearest. If |x| is not too near from 1,
this approximation should be accurate enough, and in most cases enable
one to prove that there is no underflow nor overflow.
Otherwise, it should enable one to check only underflow or overflow,
instead of both cases as in the present case.
*/
if (cmp_x_1 * MPFR_SIGN (y) > 0)
{
mpfr_t t;
int negative, overflow;
MPFR_SAVE_EXPO_MARK (expo);
mpfr_init2 (t, 53);
/* we want a lower bound on y*log2|x|:
(i) if x > 0, it suffices to round log2(x) toward zero, and
to round y*o(log2(x)) toward zero too;
(ii) if x < 0, we first compute t = o(-x), with rounding toward 1,
and then follow as in case (1). */
if (MPFR_SIGN (x) > 0)
mpfr_log2 (t, x, MPFR_RNDZ);
else
{
mpfr_neg (t, x, (cmp_x_1 > 0) ? MPFR_RNDZ : MPFR_RNDU);
mpfr_log2 (t, t, MPFR_RNDZ);
}
mpfr_mul (t, t, y, MPFR_RNDZ);
overflow = mpfr_cmp_si (t, __gmpfr_emax) > 0;
mpfr_clear (t);
MPFR_SAVE_EXPO_FREE (expo);
if (overflow)
{
MPFR_LOG_MSG (("early overflow detection\n", 0));
negative = MPFR_SIGN(x) < 0 && is_odd (y);
return mpfr_overflow (z, rnd_mode, negative ? -1 : 1);
}
}
/* Basic underflow checking. One has:
* - if y > 0, |x^y| < 2^(EXP(x) * y);
* - if y < 0, |x^y| <= 2^((EXP(x) - 1) * y);
* so that one can compute a value ebound such that |x^y| < 2^ebound.
* If we have ebound <= emin - 2 (emin - 1 in directed rounding modes),
* then there is an underflow and we can decide the return value.
*/
if (MPFR_IS_NEG (y) ? (MPFR_GET_EXP (x) > 1) : (MPFR_GET_EXP (x) < 0))
{
mpfr_t tmp;
mpfr_eexp_t ebound;
int inex2;
/* We must restore the flags. */
MPFR_SAVE_EXPO_MARK (expo);
mpfr_init2 (tmp, sizeof (mpfr_exp_t) * CHAR_BIT);
inex2 = mpfr_set_exp_t (tmp, MPFR_GET_EXP (x), MPFR_RNDN);
MPFR_ASSERTN (inex2 == 0);
if (MPFR_IS_NEG (y))
{
inex2 = mpfr_sub_ui (tmp, tmp, 1, MPFR_RNDN);
MPFR_ASSERTN (inex2 == 0);
}
mpfr_mul (tmp, tmp, y, MPFR_RNDU);
if (MPFR_IS_NEG (y))
mpfr_nextabove (tmp);
/* tmp doesn't necessarily fit in ebound, but that doesn't matter
since we get the minimum value in such a case. */
ebound = mpfr_get_exp_t (tmp, MPFR_RNDU);
mpfr_clear (tmp);
MPFR_SAVE_EXPO_FREE (expo);
if (MPFR_UNLIKELY (ebound <=
__gmpfr_emin - (rnd_mode == MPFR_RNDN ? 2 : 1)))
{
/* warning: mpfr_underflow rounds away from 0 for MPFR_RNDN */
MPFR_LOG_MSG (("early underflow detection\n", 0));
return mpfr_underflow (z,
rnd_mode == MPFR_RNDN ? MPFR_RNDZ : rnd_mode,
MPFR_SIGN (x) < 0 && is_odd (y) ? -1 : 1);
}
}
/* If y is an integer, we can use mpfr_pow_z (based on multiplications),
but if y is very large (I'm not sure about the best threshold -- VL),
we shouldn't use it, as it can be very slow and take a lot of memory
(and even crash or make other programs crash, as several hundred of
MBs may be necessary). Note that in such a case, either x = +/-2^b
(this case is handled below) or x^y cannot be represented exactly in
any precision supported by MPFR (the general case uses this property).
*/
if (y_is_integer && (MPFR_GET_EXP (y) <= 256))
{
mpz_t zi;
MPFR_LOG_MSG (("special code for y not too large integer\n", 0));
mpz_init (zi);
mpfr_get_z (zi, y, MPFR_RNDN);
inexact = mpfr_pow_z (z, x, zi, rnd_mode);
mpz_clear (zi);
return inexact;
}
/* Special case (+/-2^b)^Y which could be exact. If x is negative, then
necessarily y is a large integer. */
{
mpfr_exp_t b = MPFR_GET_EXP (x) - 1;
MPFR_ASSERTN (b >= LONG_MIN && b <= LONG_MAX); /* FIXME... */
if (mpfr_cmp_si_2exp (x, MPFR_SIGN(x), b) == 0)
{
mpfr_t tmp;
int sgnx = MPFR_SIGN (x);
MPFR_LOG_MSG (("special case (+/-2^b)^Y\n", 0));
/* now x = +/-2^b, so x^y = (+/-1)^y*2^(b*y) is exact whenever b*y is
an integer */
MPFR_SAVE_EXPO_MARK (expo);
mpfr_init2 (tmp, MPFR_PREC (y) + sizeof (long) * CHAR_BIT);
inexact = mpfr_mul_si (tmp, y, b, MPFR_RNDN); /* exact */
MPFR_ASSERTN (inexact == 0);
/* Note: as the exponent range has been extended, an overflow is not
possible (due to basic overflow and underflow checking above, as
the result is ~ 2^tmp), and an underflow is not possible either
because b is an integer (thus either 0 or >= 1). */
MPFR_CLEAR_FLAGS ();
inexact = mpfr_exp2 (z, tmp, rnd_mode);
mpfr_clear (tmp);
if (sgnx < 0 && is_odd (y))
{
mpfr_neg (z, z, rnd_mode);
inexact = -inexact;
}
/* Without the following, the overflows3 test in tpow.c fails. */
MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, __gmpfr_flags);
MPFR_SAVE_EXPO_FREE (expo);
return mpfr_check_range (z, inexact, rnd_mode);
}
}
MPFR_SAVE_EXPO_MARK (expo);
/* Case where |y * log(x)| is very small. Warning: x can be negative, in
that case y is a large integer. */
{
mpfr_t t;
mpfr_exp_t err;
/* We need an upper bound on the exponent of y * log(x). */
mpfr_init2 (t, 16);
if (MPFR_IS_POS(x))
mpfr_log (t, x, cmp_x_1 < 0 ? MPFR_RNDD : MPFR_RNDU); /* away from 0 */
else
{
/* if x < -1, round to +Inf, else round to zero */
mpfr_neg (t, x, (mpfr_cmp_si (x, -1) < 0) ? MPFR_RNDU : MPFR_RNDD);
mpfr_log (t, t, (mpfr_cmp_ui (t, 1) < 0) ? MPFR_RNDD : MPFR_RNDU);
}
MPFR_ASSERTN (MPFR_IS_PURE_FP (t));
err = MPFR_GET_EXP (y) + MPFR_GET_EXP (t);
mpfr_clear (t);
MPFR_CLEAR_FLAGS ();
MPFR_SMALL_INPUT_AFTER_SAVE_EXPO (z, __gmpfr_one, - err, 0,
(MPFR_SIGN (y) > 0) ^ (cmp_x_1 < 0),
rnd_mode, expo, {});
}
/* General case */
inexact = mpfr_pow_general (z, x, y, rnd_mode, y_is_integer, &expo);
MPFR_SAVE_EXPO_FREE (expo);
return mpfr_check_range (z, inexact, rnd_mode);
}
/* Assumes that the exponent range has already been extended and if y is
an integer, then the result is not exact in unbounded exponent range. */
int
mpfr_pow_general (mpfr_ptr z, mpfr_srcptr x, mpfr_srcptr y,
mpfr_rnd_t rnd_mode, int y_is_integer, mpfr_save_expo_t *expo)
{
mpfr_t t, u, k, absx;
int neg_result = 0;
int k_non_zero = 0;
int check_exact_case = 0;
int inexact;
/* Declaration of the size variable */
mpfr_prec_t Nz = MPFR_PREC(z); /* target precision */
mpfr_prec_t Nt; /* working precision */
mpfr_exp_t err; /* error */
MPFR_ZIV_DECL (ziv_loop);
MPFR_LOG_FUNC
(("x[%Pu]=%.*Rg y[%Pu]=%.*Rg rnd=%d",
mpfr_get_prec (x), mpfr_log_prec, x,
mpfr_get_prec (y), mpfr_log_prec, y, rnd_mode),
("z[%Pu]=%.*Rg inexact=%d",
mpfr_get_prec (z), mpfr_log_prec, z, inexact));
/* We put the absolute value of x in absx, pointing to the significand
of x to avoid allocating memory for the significand of absx. */
MPFR_ALIAS(absx, x, /*sign=*/ 1, /*EXP=*/ MPFR_EXP(x));
/* We will compute the absolute value of the result. So, let's
invert the rounding mode if the result is negative. */
if (MPFR_IS_NEG (x) && is_odd (y))
{
neg_result = 1;
rnd_mode = MPFR_INVERT_RND (rnd_mode);
}
/* compute the precision of intermediary variable */
/* the optimal number of bits : see algorithms.tex */
Nt = Nz + 5 + MPFR_INT_CEIL_LOG2 (Nz);
/* initialise of intermediary variable */
mpfr_init2 (t, Nt);
MPFR_ZIV_INIT (ziv_loop, Nt);
for (;;)
{
MPFR_BLOCK_DECL (flags1);
/* compute exp(y*ln|x|), using MPFR_RNDU to get an upper bound, so
that we can detect underflows. */
mpfr_log (t, absx, MPFR_IS_NEG (y) ? MPFR_RNDD : MPFR_RNDU); /* ln|x| */
mpfr_mul (t, y, t, MPFR_RNDU); /* y*ln|x| */
if (k_non_zero)
{
MPFR_LOG_MSG (("subtract k * ln(2)\n", 0));
mpfr_const_log2 (u, MPFR_RNDD);
mpfr_mul (u, u, k, MPFR_RNDD);
/* Error on u = k * log(2): < k * 2^(-Nt) < 1. */
mpfr_sub (t, t, u, MPFR_RNDU);
MPFR_LOG_MSG (("t = y * ln|x| - k * ln(2)\n", 0));
MPFR_LOG_VAR (t);
}
/* estimate of the error -- see pow function in algorithms.tex.
The error on t is at most 1/2 + 3*2^(EXP(t)+1) ulps, which is
<= 2^(EXP(t)+3) for EXP(t) >= -1, and <= 2 ulps for EXP(t) <= -2.
Additional error if k_no_zero: treal = t * errk, with
1 - |k| * 2^(-Nt) <= exp(-|k| * 2^(-Nt)) <= errk <= 1,
i.e., additional absolute error <= 2^(EXP(k)+EXP(t)-Nt).
Total error <= 2^err1 + 2^err2 <= 2^(max(err1,err2)+1). */
err = MPFR_NOTZERO (t) && MPFR_GET_EXP (t) >= -1 ?
MPFR_GET_EXP (t) + 3 : 1;
if (k_non_zero)
{
if (MPFR_GET_EXP (k) > err)
err = MPFR_GET_EXP (k);
err++;
}
MPFR_BLOCK (flags1, mpfr_exp (t, t, MPFR_RNDN)); /* exp(y*ln|x|)*/
/* We need to test */
if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (t) || MPFR_UNDERFLOW (flags1)))
{
mpfr_prec_t Ntmin;
MPFR_BLOCK_DECL (flags2);
MPFR_ASSERTN (!k_non_zero);
MPFR_ASSERTN (!MPFR_IS_NAN (t));
/* Real underflow? */
if (MPFR_IS_ZERO (t))
{
/* Underflow. We computed rndn(exp(t)), where t >= y*ln|x|.
Therefore rndn(|x|^y) = 0, and we have a real underflow on
|x|^y. */
inexact = mpfr_underflow (z, rnd_mode == MPFR_RNDN ? MPFR_RNDZ
: rnd_mode, MPFR_SIGN_POS);
if (expo != NULL)
MPFR_SAVE_EXPO_UPDATE_FLAGS (*expo, MPFR_FLAGS_INEXACT
| MPFR_FLAGS_UNDERFLOW);
break;
}
/* Real overflow? */
if (MPFR_IS_INF (t))
{
/* Note: we can probably use a low precision for this test. */
mpfr_log (t, absx, MPFR_IS_NEG (y) ? MPFR_RNDU : MPFR_RNDD);
mpfr_mul (t, y, t, MPFR_RNDD); /* y * ln|x| */
MPFR_BLOCK (flags2, mpfr_exp (t, t, MPFR_RNDD));
/* t = lower bound on exp(y * ln|x|) */
if (MPFR_OVERFLOW (flags2))
{
/* We have computed a lower bound on |x|^y, and it
overflowed. Therefore we have a real overflow
on |x|^y. */
inexact = mpfr_overflow (z, rnd_mode, MPFR_SIGN_POS);
if (expo != NULL)
MPFR_SAVE_EXPO_UPDATE_FLAGS (*expo, MPFR_FLAGS_INEXACT
| MPFR_FLAGS_OVERFLOW);
break;
}
}
k_non_zero = 1;
Ntmin = sizeof(mpfr_exp_t) * CHAR_BIT;
if (Ntmin > Nt)
{
Nt = Ntmin;
mpfr_set_prec (t, Nt);
}
mpfr_init2 (u, Nt);
mpfr_init2 (k, Ntmin);
mpfr_log2 (k, absx, MPFR_RNDN);
mpfr_mul (k, y, k, MPFR_RNDN);
mpfr_round (k, k);
MPFR_LOG_VAR (k);
/* |y| < 2^Ntmin, therefore |k| < 2^Nt. */
continue;
}
if (MPFR_LIKELY (MPFR_CAN_ROUND (t, Nt - err, Nz, rnd_mode)))
{
inexact = mpfr_set (z, t, rnd_mode);
break;
}
/* check exact power, except when y is an integer (since the
exact cases for y integer have already been filtered out) */
if (check_exact_case == 0 && ! y_is_integer)
{
if (mpfr_pow_is_exact (z, absx, y, rnd_mode, &inexact))
break;
check_exact_case = 1;
}
/* reactualisation of the precision */
MPFR_ZIV_NEXT (ziv_loop, Nt);
mpfr_set_prec (t, Nt);
if (k_non_zero)
mpfr_set_prec (u, Nt);
}
MPFR_ZIV_FREE (ziv_loop);
if (k_non_zero)
{
int inex2;
long lk;
/* The rounded result in an unbounded exponent range is z * 2^k. As
* MPFR chooses underflow after rounding, the mpfr_mul_2si below will
* correctly detect underflows and overflows. However, in rounding to
* nearest, if z * 2^k = 2^(emin - 2), then the double rounding may
* affect the result. We need to cope with that before overwriting z.
* This can occur only if k < 0 (this test is necessary to avoid a
* potential integer overflow).
* If inexact >= 0, then the real result is <= 2^(emin - 2), so that
* o(2^(emin - 2)) = +0 is correct. If inexact < 0, then the real
* result is > 2^(emin - 2) and we need to round to 2^(emin - 1).
*/
MPFR_ASSERTN (MPFR_EXP_MAX <= LONG_MAX);
lk = mpfr_get_si (k, MPFR_RNDN);
/* Due to early overflow detection, |k| should not be much larger than
* MPFR_EMAX_MAX, and as MPFR_EMAX_MAX <= MPFR_EXP_MAX/2 <= LONG_MAX/2,
* an overflow should not be possible in mpfr_get_si (and lk is exact).
* And one even has the following assertion. TODO: complete proof.
*/
MPFR_ASSERTD (lk > LONG_MIN && lk < LONG_MAX);
/* Note: even in case of overflow (lk inexact), the code is correct.
* Indeed, for the 3 occurrences of lk:
* - The test lk < 0 is correct as sign(lk) = sign(k).
* - In the test MPFR_GET_EXP (z) == __gmpfr_emin - 1 - lk,
* if lk is inexact, then lk = LONG_MIN <= MPFR_EXP_MIN
* (the minimum value of the mpfr_exp_t type), and
* __gmpfr_emin - 1 - lk >= MPFR_EMIN_MIN - 1 - 2 * MPFR_EMIN_MIN
* >= - MPFR_EMIN_MIN - 1 = MPFR_EMAX_MAX - 1. However, from the
* choice of k, z has been chosen to be around 1, so that the
* result of the test is false, as if lk were exact.
* - In the mpfr_mul_2si (z, z, lk, rnd_mode), if lk is inexact,
* then |lk| >= LONG_MAX >= MPFR_EXP_MAX, and as z is around 1,
* mpfr_mul_2si underflows or overflows in the same way as if
* lk were exact.
* TODO: give a bound on |t|, then on |EXP(z)|.
*/
if (rnd_mode == MPFR_RNDN && inexact < 0 && lk < 0 &&
MPFR_GET_EXP (z) == __gmpfr_emin - 1 - lk && mpfr_powerof2_raw (z))
{
/* Rounding to nearest, real result > z * 2^k = 2^(emin - 2),
* underflow case: as the minimum precision is > 1, we will
* obtain the correct result and exceptions by replacing z by
* nextabove(z).
*/
MPFR_ASSERTN (MPFR_PREC_MIN > 1);
mpfr_nextabove (z);
}
MPFR_CLEAR_FLAGS ();
inex2 = mpfr_mul_2si (z, z, lk, rnd_mode);
if (inex2) /* underflow or overflow */
{
inexact = inex2;
if (expo != NULL)
MPFR_SAVE_EXPO_UPDATE_FLAGS (*expo, __gmpfr_flags);
}
mpfr_clears (u, k, (mpfr_ptr) 0);
}
mpfr_clear (t);
/* update the sign of the result if x was negative */
if (neg_result)
{
MPFR_SET_NEG(z);
inexact = -inexact;
}
return inexact;
}
static void
check_nan (void)
{
mpfr_t a, d, q;
mp_exp_t emax, emin;
mpfr_init2 (a, 100L);
mpfr_init2 (d, 100L);
mpfr_init2 (q, 100L);
/* 1/nan == nan */
mpfr_set_ui (a, 1L, GMP_RNDN);
MPFR_SET_NAN (d);
MPFR_ASSERTN (test_div (q, a, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_nan_p (q));
/* nan/1 == nan */
MPFR_SET_NAN (a);
mpfr_set_ui (d, 1L, GMP_RNDN);
MPFR_ASSERTN (test_div (q, a, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_nan_p (q));
/* +inf/1 == +inf */
MPFR_CLEAR_FLAGS (a);
MPFR_SET_INF (a);
MPFR_SET_POS (a);
mpfr_set_ui (d, 1L, GMP_RNDN);
MPFR_ASSERTN (test_div (q, a, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_inf_p (q));
MPFR_ASSERTN (mpfr_sgn (q) > 0);
/* 1/+inf == 0 */
mpfr_set_ui (a, 1L, GMP_RNDN);
MPFR_CLEAR_FLAGS (d);
MPFR_SET_INF (d);
MPFR_SET_POS (d);
MPFR_ASSERTN (test_div (q, a, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_number_p (q));
MPFR_ASSERTN (mpfr_sgn (q) == 0);
/* 0/0 == nan */
mpfr_set_ui (a, 0L, GMP_RNDN);
mpfr_set_ui (d, 0L, GMP_RNDN);
MPFR_ASSERTN (test_div (q, a, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_nan_p (q));
/* +inf/+inf == nan */
MPFR_CLEAR_FLAGS (a);
MPFR_SET_INF (a);
MPFR_SET_POS (a);
MPFR_CLEAR_FLAGS (d);
MPFR_SET_INF (d);
MPFR_SET_POS (d);
MPFR_ASSERTN (test_div (q, a, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_nan_p (q));
/* 1/+0 = +Inf */
mpfr_set_ui (a, 1, GMP_RNDZ);
mpfr_set_ui (d, 0, GMP_RNDZ);
MPFR_ASSERTN (test_div (q, a, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_inf_p (q) && mpfr_sgn (q) > 0);
/* 1/-0 = -Inf */
mpfr_set_ui (a, 1, GMP_RNDZ);
mpfr_set_ui (d, 0, GMP_RNDZ);
mpfr_neg (d, d, GMP_RNDZ);
MPFR_ASSERTN (test_div (q, a, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_inf_p (q) && mpfr_sgn (q) < 0);
/* -1/+0 = -Inf */
mpfr_set_si (a, -1, GMP_RNDZ);
mpfr_set_ui (d, 0, GMP_RNDZ);
MPFR_ASSERTN (test_div (q, a, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_inf_p (q) && mpfr_sgn (q) < 0);
/* -1/-0 = +Inf */
mpfr_set_si (a, -1, GMP_RNDZ);
mpfr_set_ui (d, 0, GMP_RNDZ);
mpfr_neg (d, d, GMP_RNDZ);
MPFR_ASSERTN (test_div (q, a, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_inf_p (q) && mpfr_sgn (q) > 0);
/* check overflow */
emax = mpfr_get_emax ();
set_emax (1);
mpfr_set_ui (a, 1, GMP_RNDZ);
mpfr_set_ui (d, 1, GMP_RNDZ);
mpfr_div_2exp (d, d, 1, GMP_RNDZ);
test_div (q, a, d, GMP_RNDU); /* 1 / 0.5 = 2 -> overflow */
MPFR_ASSERTN (mpfr_inf_p (q) && mpfr_sgn (q) > 0);
set_emax (emax);
/* check underflow */
emin = mpfr_get_emin ();
set_emin (-1);
mpfr_set_ui (a, 1, GMP_RNDZ);
mpfr_div_2exp (a, a, 2, GMP_RNDZ);
mpfr_set_ui (d, 2, GMP_RNDZ);
test_div (q, a, d, GMP_RNDZ); /* 0.5*2^(-2) -> underflow */
MPFR_ASSERTN (mpfr_cmp_ui (q, 0) == 0 && MPFR_IS_POS (q));
test_div (q, a, d, GMP_RNDN); /* 0.5*2^(-2) -> underflow */
MPFR_ASSERTN (mpfr_cmp_ui (q, 0) == 0 && MPFR_IS_POS (q));
set_emin (emin);
mpfr_clear (a);
mpfr_clear (d);
mpfr_clear (q);
}
int
mpfr_sub (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mp_rnd_t rnd_mode)
{
MPFR_LOG_FUNC (("b[%#R]=%R c[%#R]=%R rnd=%d", b, b, c, c, rnd_mode),
("a[%#R]=%R", a, a));
if (MPFR_ARE_SINGULAR (b,c))
{
if (MPFR_IS_NAN (b) || MPFR_IS_NAN (c))
{
MPFR_SET_NAN (a);
MPFR_RET_NAN;
}
else if (MPFR_IS_INF (b))
{
if (!MPFR_IS_INF (c) || MPFR_SIGN (b) != MPFR_SIGN(c))
{
MPFR_SET_INF (a);
MPFR_SET_SAME_SIGN (a, b);
MPFR_RET (0); /* exact */
}
else
{
MPFR_SET_NAN (a); /* Inf - Inf */
MPFR_RET_NAN;
}
}
else if (MPFR_IS_INF (c))
{
MPFR_SET_INF (a);
MPFR_SET_OPPOSITE_SIGN (a, c);
MPFR_RET (0); /* exact */
}
else if (MPFR_IS_ZERO (b))
{
if (MPFR_IS_ZERO (c))
{
int sign = rnd_mode != GMP_RNDD
? ((MPFR_IS_NEG(b) && MPFR_IS_POS(c)) ? -1 : 1)
: ((MPFR_IS_POS(b) && MPFR_IS_NEG(c)) ? 1 : -1);
MPFR_SET_SIGN (a, sign);
MPFR_SET_ZERO (a);
MPFR_RET(0); /* 0 - 0 is exact */
}
else
return mpfr_neg (a, c, rnd_mode);
}
else
{
MPFR_ASSERTD (MPFR_IS_ZERO (c));
return mpfr_set (a, b, rnd_mode);
}
}
MPFR_CLEAR_FLAGS (a);
MPFR_ASSERTD (MPFR_IS_PURE_FP (b) && MPFR_IS_PURE_FP (c));
if (MPFR_LIKELY (MPFR_SIGN (b) == MPFR_SIGN (c)))
{ /* signs are equal, it's a real subtraction */
if (MPFR_LIKELY (MPFR_PREC (a) == MPFR_PREC (b)
&& MPFR_PREC (b) == MPFR_PREC (c)))
return mpfr_sub1sp (a, b, c, rnd_mode);
else
return mpfr_sub1 (a, b, c, rnd_mode);
}
else
{ /* signs differ, it's an addition */
if (MPFR_GET_EXP (b) < MPFR_GET_EXP (c))
{ /* exchange rounding modes toward +/- infinity */
int inexact;
rnd_mode = MPFR_INVERT_RND (rnd_mode);
if (MPFR_LIKELY (MPFR_PREC (a) == MPFR_PREC (b)
&& MPFR_PREC (b) == MPFR_PREC (c)))
inexact = mpfr_add1sp (a, c, b, rnd_mode);
else
inexact = mpfr_add1 (a, c, b, rnd_mode);
MPFR_CHANGE_SIGN (a);
return -inexact;
}
else
{
if (MPFR_LIKELY (MPFR_PREC (a) == MPFR_PREC (b)
&& MPFR_PREC (b) == MPFR_PREC (c)))
return mpfr_add1sp (a, b, c, rnd_mode);
else
return mpfr_add1 (a, b, c, rnd_mode);
}
}
}
/* Compute the first 2^m terms from the hypergeometric series
with x = p / 2^r */
static int
GENERIC (mpfr_ptr y, mpz_srcptr p, long r, int m)
{
unsigned long n,i,k,j,l;
int is_p_one;
mpz_t* P,*S;
#ifdef A
mpz_t *T;
#endif
mpz_t* ptoj;
#ifdef R_IS_RATIONAL
mpz_t* qtoj;
mpfr_t tmp;
#endif
mp_exp_t diff, expo;
mp_prec_t precy = MPFR_PREC(y);
MPFR_TMP_DECL(marker);
MPFR_TMP_MARK(marker);
MPFR_CLEAR_FLAGS(y);
n = 1UL << m;
P = (mpz_t*) MPFR_TMP_ALLOC ((m+1) * sizeof(mpz_t));
S = (mpz_t*) MPFR_TMP_ALLOC ((m+1) * sizeof(mpz_t));
ptoj = (mpz_t*) MPFR_TMP_ALLOC ((m+1) * sizeof(mpz_t)); /* ptoj[i] = mantissa^(2^i) */
#ifdef A
T = (mpz_t*) MPFR_TMP_ALLOC ((m+1) * sizeof(mpz_t));
#endif
#ifdef R_IS_RATIONAL
qtoj = (mpz_t*) MPFR_TMP_ALLOC ((m+1) * sizeof(mpz_t));
#endif
for (i = 0 ; i <= m ; i++)
{
mpz_init (P[i]);
mpz_init (S[i]);
mpz_init (ptoj[i]);
#ifdef R_IS_RATIONAL
mpz_init (qtoj[i]);
#endif
#ifdef A
mpz_init (T[i]);
#endif
}
mpz_set (ptoj[0], p);
#ifdef C
# if C2 != 1
mpz_mul_ui (ptoj[0], ptoj[0], C2);
# endif
#endif
is_p_one = mpz_cmp_ui(ptoj[0], 1) == 0;
#ifdef A
# ifdef B
mpz_set_ui (T[0], A1 * B1);
# else
mpz_set_ui (T[0], A1);
# endif
#endif
if (!is_p_one)
for (i = 1 ; i < m ; i++)
mpz_mul (ptoj[i], ptoj[i-1], ptoj[i-1]);
#ifdef R_IS_RATIONAL
mpz_set_si (qtoj[0], r);
for (i = 1 ; i <= m ; i++)
mpz_mul(qtoj[i], qtoj[i-1], qtoj[i-1]);
#endif
mpz_set_ui (P[0], 1);
mpz_set_ui (S[0], 1);
k = 0;
for (i = 1 ; i < n ; i++) {
k++;
#ifdef A
# ifdef B
mpz_set_ui (T[k], (A1 + A2*i)*(B1+B2*i));
# else
mpz_set_ui (T[k], A1 + A2*i);
# endif
#endif
#ifdef C
# ifdef NO_FACTORIAL
mpz_set_ui (P[k], (C1 + C2 * (i-1)));
mpz_set_ui (S[k], 1);
# else
mpz_set_ui (P[k], (i+1) * (C1 + C2 * (i-1)));
mpz_set_ui (S[k], i+1);
# endif
#else
# ifdef NO_FACTORIAL
mpz_set_ui (P[k], 1);
# else
mpz_set_ui (P[k], i+1);
# endif
mpz_set (S[k], P[k]);
#endif
for (j = i+1, l = 0 ; (j & 1) == 0 ; l++, j>>=1, k--) {
if (!is_p_one)
mpz_mul (S[k], S[k], ptoj[l]);
#ifdef A
# ifdef B
# if (A2*B2) != 1
mpz_mul_ui (P[k], P[k], A2*B2);
# endif
# else
# if A2 != 1
mpz_mul_ui (P[k], P[k], A2);
# endif
#endif
mpz_mul (S[k], S[k], T[k-1]);
#endif
mpz_mul (S[k-1], S[k-1], P[k]);
#ifdef R_IS_RATIONAL
mpz_mul (S[k-1], S[k-1], qtoj[l]);
#else
mpz_mul_2exp (S[k-1], S[k-1], r*(1<<l));
#endif
mpz_add (S[k-1], S[k-1], S[k]);
mpz_mul (P[k-1], P[k-1], P[k]);
#ifdef A
mpz_mul (T[k-1], T[k-1], T[k]);
#endif
}
}
diff = mpz_sizeinbase(S[0],2) - 2*precy;
expo = diff;
if (diff >= 0)
mpz_div_2exp(S[0],S[0],diff);
else
mpz_mul_2exp(S[0],S[0],-diff);
diff = mpz_sizeinbase(P[0],2) - precy;
expo -= diff;
if (diff >=0)
mpz_div_2exp(P[0],P[0],diff);
else
mpz_mul_2exp(P[0],P[0],-diff);
mpz_tdiv_q(S[0], S[0], P[0]);
mpfr_set_z(y, S[0], GMP_RNDD);
MPFR_SET_EXP (y, MPFR_GET_EXP (y) + expo);
#ifdef R_IS_RATIONAL
/* exact division */
mpz_div_ui (qtoj[m], qtoj[m], r);
mpfr_init2 (tmp, MPFR_PREC(y));
mpfr_set_z (tmp, qtoj[m] , GMP_RNDD);
mpfr_div (y, y, tmp, GMP_RNDD);
mpfr_clear (tmp);
#else
mpfr_div_2ui(y, y, r*(i-1), GMP_RNDN);
#endif
for (i = 0 ; i <= m ; i++)
{
mpz_clear (P[i]);
mpz_clear (S[i]);
mpz_clear (ptoj[i]);
#ifdef R_IS_RATIONAL
mpz_clear (qtoj[i]);
#endif
#ifdef A
mpz_clear (T[i]);
#endif
}
MPFR_TMP_FREE (marker);
return 0;
}
int
main (int argc, char *argv[])
{
mpfr_t x, y, z, ax;
long int iy;
mpfr_init (x);
mpfr_init (ax);
mpfr_init2 (y,sizeof(unsigned long int)*CHAR_BIT);
mpfr_init (z);
MPFR_SET_NAN(x);
mpfr_random(y);
mpfr_pow (z, x,y, GMP_RNDN);
if(!MPFR_IS_NAN(z))
{
printf ("evaluation of function in x=NAN does not return NAN");
exit (1);
}
MPFR_SET_NAN(y);
mpfr_random(x);
mpfr_pow (z, x,y, GMP_RNDN);
if(!MPFR_IS_NAN(z))
{
printf ("evaluation of function in y=NAN does not return NAN");
exit (1);
}
MPFR_CLEAR_FLAGS(z);
MPFR_CLEAR_FLAGS(y);
MPFR_CLEAR_FLAGS(x);
MPFR_SET_ZERO(y);
mpfr_random(x);
mpfr_pow (z, x,y, GMP_RNDN);
if(mpfr_cmp_ui(z,1)!=0 && !(MPFR_IS_NAN(x)))
{
printf ("evaluation of function in y=0 does not return 1\n");
printf ("x =");
mpfr_out_str (stdout, 10, MPFR_PREC(x), x, GMP_RNDN);
printf ("\n y =");
mpfr_out_str (stdout, 10, MPFR_PREC(y), y, GMP_RNDN);
printf ("\n result =");
mpfr_out_str (stdout, 10, MPFR_PREC(z), z, GMP_RNDN);
exit (1);
}
MPFR_CLEAR_FLAGS(z);
MPFR_CLEAR_FLAGS(y);
MPFR_CLEAR_FLAGS(x);
MPFR_SET_INF(y);
if (MPFR_SIGN(y) < 0)
MPFR_CHANGE_SIGN(y);
mpfr_random(x);
mpfr_set_prec (ax, MPFR_PREC(x));
mpfr_abs(ax,x,GMP_RNDN);
mpfr_pow (z, x,y, GMP_RNDN);
if( !MPFR_IS_INF(z) && (mpfr_cmp_ui(ax,1) > 0) )
{
printf ("evaluation of function in y=INF (|x|>1) does not return INF");
exit (1);
}
if( !MPFR_IS_ZERO(z) && (mpfr_cmp_ui(ax,1) < 0) )
{
printf ("\nevaluation of function in y=INF (|x|<1) does not return 0");
printf ("\nx =");
mpfr_out_str (stdout, 10, MPFR_PREC(x), x, GMP_RNDN);
printf ("\n y =");
mpfr_out_str (stdout, 10, MPFR_PREC(y), y, GMP_RNDN);
printf ("\n result =");
mpfr_out_str (stdout, 10, MPFR_PREC(z), z, GMP_RNDN);
putchar('\n');
exit (1);
}
MPFR_CLEAR_FLAGS(z);
MPFR_CLEAR_FLAGS(y);
MPFR_CLEAR_FLAGS(x);
MPFR_SET_INF(y);
if (MPFR_SIGN(y) > 0)
MPFR_CHANGE_SIGN(y);
mpfr_random(x);
mpfr_set_prec (ax, MPFR_PREC(x));
mpfr_abs(ax,x,GMP_RNDN);
mpfr_pow (z, x,y, GMP_RNDN);
mpfr_pow (z, x,y, GMP_RNDN);
if( !MPFR_IS_INF(z) && (mpfr_cmp_ui(ax,1) < 0) )
{
printf ("evaluation of function in y=INF (for |x| <0) does not return INF");
exit (1);
}
if( !MPFR_IS_ZERO(z) && (mpfr_cmp_ui(ax,1) > 0) )
{
printf ("evaluation of function in y=INF (for |x| >0) does not return 0");
exit (1);
}
MPFR_CLEAR_FLAGS(z);
MPFR_CLEAR_FLAGS(y);
MPFR_CLEAR_FLAGS(x);
MPFR_SET_INF(x);
if (MPFR_SIGN(x) < 0)
MPFR_CHANGE_SIGN(x);
mpfr_random(y);
mpfr_pow (z, x,y, GMP_RNDN);
if(!MPFR_IS_INF(z) && (MPFR_SIGN(y) > 0))
{
printf ("evaluation of function in INF does not return INF");
printf ("\nx =");
mpfr_out_str (stdout, 10, MPFR_PREC(x), x, GMP_RNDN);
printf ("\n y =");
mpfr_out_str (stdout, 10, MPFR_PREC(y), y, GMP_RNDN);
printf ("\n result =");
mpfr_out_str (stdout, 10, MPFR_PREC(z), z, GMP_RNDN);
putchar('\n');
exit (1);
}
if(!MPFR_IS_ZERO(z) && (MPFR_SIGN(y) < 0))
{
printf ("evaluation of function in INF does not return INF");
printf ("\nx =");
mpfr_out_str (stdout, 10, MPFR_PREC(x), x, GMP_RNDN);
printf ("\n y =");
mpfr_out_str (stdout, 10, MPFR_PREC(y), y, GMP_RNDN);
printf ("\n result =");
mpfr_out_str (stdout, 10, MPFR_PREC(z), z, GMP_RNDN);
putchar('\n');
exit (1);
}
MPFR_CLEAR_FLAGS(z);
MPFR_CLEAR_FLAGS(y);
MPFR_CLEAR_FLAGS(x);
MPFR_SET_INF(x);
if (MPFR_SIGN(x) > 0)
MPFR_CHANGE_SIGN(x);
mpfr_random(y);
if (random() % 2)
mpfr_neg (y, y, GMP_RNDN);
mpfr_pow (z, x,y, GMP_RNDN);
if(!MPFR_IS_INF(z) && (MPFR_SIGN(y) > 0) && (mpfr_isinteger(y)))
{
printf ("evaluation of function in x=-INF does not return INF");
printf ("\nx =");
mpfr_out_str (stdout, 10, MPFR_PREC(x), x, GMP_RNDN);
printf ("\n y =");
mpfr_out_str (stdout, 10, MPFR_PREC(y), y, GMP_RNDN);
printf ("\n result =");
mpfr_out_str (stdout, 10, MPFR_PREC(z), z, GMP_RNDN);
putchar('\n');
if(mpfr_isinteger(y))
printf("y is an integer\n");
else
printf("y is not an integer\n");
exit (1);
}
if(!MPFR_IS_ZERO(z) && (MPFR_SIGN(y) < 0) && (mpfr_isinteger(y)))
{
printf ("evaluation of function in x=-INF does not return 0");
printf ("\nx =");
mpfr_out_str (stdout, 10, MPFR_PREC(x), x, GMP_RNDN);
printf ("\n y =");
mpfr_out_str (stdout, 10, MPFR_PREC(y), y, GMP_RNDN);
printf ("\n result =");
mpfr_out_str (stdout, 10, MPFR_PREC(z), z, GMP_RNDN);
putchar('\n');
if(mpfr_isinteger(y))
printf("y is an integer\n");
else
printf("y is not an integer\n");
exit (1);
}
MPFR_CLEAR_FLAGS(z);
MPFR_CLEAR_FLAGS(y);
MPFR_CLEAR_FLAGS(x);
MPFR_SET_INF(x);
if (MPFR_SIGN(x) > 0)
MPFR_CHANGE_SIGN(x);
iy=random();
mpfr_random(y);
if (random() % 2)
iy=-iy;
mpfr_set_d(y,iy,GMP_RNDN);
mpfr_pow (z, x,y, GMP_RNDN);
if(!MPFR_IS_INF(z) && (MPFR_SIGN(y) > 0) && (mpfr_isinteger(y)))
{
printf ("evaluation of function in x=-INF does not return INF");
printf ("\nx =");
mpfr_out_str (stdout, 10, MPFR_PREC(x), x, GMP_RNDN);
printf ("\n y =");
mpfr_out_str (stdout, 10, MPFR_PREC(y), y, GMP_RNDN);
printf ("\n result =");
mpfr_out_str (stdout, 10, MPFR_PREC(z), z, GMP_RNDN);
putchar('\n');
if(mpfr_isinteger(y))
printf("y is an integer\n");
else
printf("y is not an integer\n");
exit (1);
}
if(!MPFR_IS_ZERO(z) && (MPFR_SIGN(y) < 0) && (mpfr_isinteger(y)))
{
printf ("evaluation of function in x=-INF does not return 0");
printf ("\nx =");
mpfr_out_str (stdout, 10, MPFR_PREC(x), x, GMP_RNDN);
printf ("\n y =");
mpfr_out_str (stdout, 10, MPFR_PREC(y), y, GMP_RNDN);
printf ("\n result =");
mpfr_out_str (stdout, 10, MPFR_PREC(z), z, GMP_RNDN);
putchar('\n');
if(mpfr_isinteger(y))
printf("y is an integer\n");
else
printf("y is not an integer\n");
exit (1);
}
MPFR_CLEAR_FLAGS(z);
MPFR_CLEAR_FLAGS(y);
MPFR_CLEAR_FLAGS(x);
mpfr_set_ui(x,1,GMP_RNDN);
MPFR_SET_INF(y);
mpfr_pow (z, x,y, GMP_RNDN);
if(!MPFR_IS_NAN(z))
{
printf ("evaluation of function in x=1, y=INF does not return NAN");
printf ("\nx =");
mpfr_out_str (stdout, 10, MPFR_PREC(x), x, GMP_RNDN);
printf ("\n y =");
mpfr_out_str (stdout, 10, MPFR_PREC(y), y, GMP_RNDN);
printf ("\n result =");
mpfr_out_str (stdout, 10, MPFR_PREC(z), z, GMP_RNDN);
putchar('\n');
exit (1);
}
MPFR_CLEAR_FLAGS(z);
MPFR_CLEAR_FLAGS(y);
MPFR_CLEAR_FLAGS(x);
MPFR_SET_ZERO(x);
mpfr_random(y);
if (random() % 2)
mpfr_neg (y, y, GMP_RNDN);
mpfr_pow (z, x,y, GMP_RNDN);
if(!MPFR_IS_ZERO(z) && (MPFR_SIGN(y) < 0) && !(mpfr_isinteger(y)))
{
printf ("evaluation of function in y<0 does not return 0");
printf ("\nx =");
mpfr_out_str (stdout, 10, MPFR_PREC(x), x, GMP_RNDN);
printf ("\n y =");
mpfr_out_str (stdout, 10, MPFR_PREC(y), y, GMP_RNDN);
printf ("\n result =");
mpfr_out_str (stdout, 10, MPFR_PREC(z), z, GMP_RNDN);
putchar('\n');
exit (1);
}
if(!MPFR_IS_INF(z) && (MPFR_SIGN(y) < 0) && (mpfr_isinteger(y)))
{
printf ("evaluation of function in y<0 (y integer) does not return INF");
printf ("\nx =");
mpfr_out_str (stdout, 10, MPFR_PREC(x), x, GMP_RNDN);
printf ("\n y =");
mpfr_out_str (stdout, 10, MPFR_PREC(y), y, GMP_RNDN);
printf ("\n result =");
mpfr_out_str (stdout, 10, MPFR_PREC(z), z, GMP_RNDN);
putchar('\n');
exit (1);
}
if(!MPFR_IS_ZERO(z) && (MPFR_SIGN(y) > 0) && (mpfr_isinteger(y)))
{
printf ("evaluation of function in y<0 (y integer) does not return 0");
printf ("\nx =");
mpfr_out_str (stdout, 10, MPFR_PREC(x), x, GMP_RNDN);
printf ("\n y =");
mpfr_out_str (stdout, 10, MPFR_PREC(y), y, GMP_RNDN);
printf ("\n result =");
mpfr_out_str (stdout, 10, MPFR_PREC(z), z, GMP_RNDN);
putchar('\n');
exit (1);
}
{
mp_prec_t prec, yprec;
mpfr_t t, s;
mp_rnd_t rnd;
int inexact, compare, compare2;
unsigned int n, err;
int p0=2;
int p1=100;
int N=100;
mpfr_init (s);
mpfr_init (t);
/* generic test */
for (prec = p0; prec <= p1; prec++)
{
mpfr_set_prec (x, prec);
mpfr_set_prec (s, sizeof(unsigned long int)*CHAR_BIT);
mpfr_set_prec (z, prec);
mpfr_set_prec (t, prec);
yprec = prec + 10;
for (n=0; n<N; n++)
{
mpfr_random (x);
mpfr_random (s);
if (random() % 2)
mpfr_neg (s, s, GMP_RNDN);
rnd = random () % 4;
mpfr_set_prec (y, yprec);
compare = mpfr_pow (y, x, s, rnd);
err = (rnd == GMP_RNDN) ? yprec + 1 : yprec;
if (mpfr_can_round (y, err, rnd, rnd, prec))
{
mpfr_set (t, y, rnd);
inexact = mpfr_pow (z,x, s, rnd);
if (mpfr_cmp (t, z))
{
printf ("results differ for x=");
mpfr_out_str (stdout, 2, prec, x, GMP_RNDN);
printf (" values of the exponential=");
mpfr_out_str (stdout, 2, prec, s, GMP_RNDN);
printf (" prec=%u rnd_mode=%s\n", (unsigned) prec,
mpfr_print_rnd_mode (rnd));
printf ("got ");
mpfr_out_str (stdout, 2, prec, z, GMP_RNDN);
putchar ('\n');
printf ("expected ");
mpfr_out_str (stdout, 2, prec, t, GMP_RNDN);
putchar ('\n');
printf ("approx ");
mpfr_print_binary (y);
putchar ('\n');
exit (1);
}
compare2 = mpfr_cmp (t, y);
/* if rounding to nearest, cannot know the sign of t - f(x)
because of composed rounding: y = o(f(x)) and t = o(y) */
if ((rnd != GMP_RNDN) && (compare * compare2 >= 0))
compare = compare + compare2;
else
compare = inexact; /* cannot determine sign(t-f(x)) */
if (((inexact == 0) && (compare != 0)) ||
((inexact > 0) && (compare <= 0)) ||
((inexact < 0) && (compare >= 0)))
{
fprintf (stderr, "Wrong inexact flag for rnd=%s: expected %d, got %d\n",
mpfr_print_rnd_mode (rnd), compare, inexact);
printf ("x="); mpfr_print_binary (x); putchar ('\n');
printf ("y="); mpfr_print_binary (y); putchar ('\n');
printf ("t="); mpfr_print_binary (t); putchar ('\n');
exit (1);
}
}
}
}
mpfr_clear (s);
mpfr_clear (t);
}
mpfr_clear (x);
mpfr_clear (y);
mpfr_clear (z);
mpfr_clear (ax);
return 0;
}
int
mpfr_frac (mpfr_ptr r, mpfr_srcptr u, mp_rnd_t rnd_mode)
{
mp_exp_t re, ue;
mp_prec_t uq, fq;
mp_size_t un, tn, t0;
mp_limb_t *up, *tp, k;
int sh;
mpfr_t tmp;
mpfr_ptr t;
/* Special cases */
if (MPFR_UNLIKELY(MPFR_IS_NAN(u)))
{
MPFR_SET_NAN(r);
MPFR_RET_NAN;
}
else if (MPFR_UNLIKELY(MPFR_IS_INF(u) || mpfr_integer_p (u)))
{
MPFR_CLEAR_FLAGS(r);
MPFR_SET_SAME_SIGN(r, u);
MPFR_SET_ZERO(r);
MPFR_RET(0); /* zero is exact */
}
ue = MPFR_GET_EXP (u);
if (ue <= 0) /* |u| < 1 */
return mpfr_set (r, u, rnd_mode);
uq = MPFR_PREC(u);
un = (uq - 1) / BITS_PER_MP_LIMB; /* index of most significant limb */
un -= (mp_size_t) (ue / BITS_PER_MP_LIMB);
/* now the index of the MSL containing bits of the fractional part */
up = MPFR_MANT(u);
sh = ue % BITS_PER_MP_LIMB;
k = up[un] << sh;
/* the first bit of the fractional part is the MSB of k */
if (k != 0)
{
int cnt;
count_leading_zeros(cnt, k);
/* first bit 1 of the fractional part -> MSB of the number */
re = -cnt;
sh += cnt;
MPFR_ASSERTN (sh < BITS_PER_MP_LIMB);
k <<= cnt;
}
else
{
re = sh - BITS_PER_MP_LIMB;
/* searching for the first bit 1 (exists since u isn't an integer) */
while (up[--un] == 0)
re -= BITS_PER_MP_LIMB;
MPFR_ASSERTN(un >= 0);
k = up[un];
count_leading_zeros(sh, k);
re -= sh;
k <<= sh;
}
/* The exponent of r will be re */
/* un: index of the limb of u that contains the first bit 1 of the FP */
ue -= re; /* number of bits of u to discard */
fq = uq - ue; /* number of bits of the fractional part of u */
/* Temporary fix */
t = /* fq > MPFR_PREC(r) */
(mp_size_t) (MPFR_PREC(r) - 1) / BITS_PER_MP_LIMB < un ?
(mpfr_init2 (tmp, (un + 1) * BITS_PER_MP_LIMB), tmp) : r;
/* t has enough precision to contain the fractional part of u */
/* If we use a temporary variable, we take the non-significant bits
of u into account, because of the mpn_lshift below. */
MPFR_CLEAR_FLAGS(t);
MPFR_SET_SAME_SIGN(t, u);
MPFR_SET_EXP (t, re);
/* Put the fractional part of u into t */
tn = (MPFR_PREC(t) - 1) / BITS_PER_MP_LIMB;
MPFR_ASSERTN(tn >= un);
t0 = tn - un;
tp = MPFR_MANT(t);
if (sh == 0)
MPN_COPY_DECR(tp + t0, up, un + 1);
else /* warning: un may be 0 here */
tp[tn] = k | ((un) ? mpn_lshift (tp + t0, up, un, sh) : (mp_limb_t) 0);
if (t0 > 0)
MPN_ZERO(tp, t0);
if (t != r)
{ /* t is tmp */
int inex;
inex = mpfr_set (r, t, rnd_mode);
mpfr_clear (t);
return inex;
}
else
MPFR_RET(0);
}
/* agm(x,y) is between x and y, so we don't need to save exponent range */
int
mpfr_agm (mpfr_ptr r, mpfr_srcptr op2, mpfr_srcptr op1, mp_rnd_t rnd_mode)
{
int compare, inexact;
mp_size_t s;
mp_prec_t p, q;
mp_limb_t *up, *vp, *tmpp;
mpfr_t u, v, tmp;
unsigned long n; /* number of iterations */
unsigned long err = 0;
MPFR_ZIV_DECL (loop);
MPFR_TMP_DECL(marker);
MPFR_LOG_FUNC (("op2[%#R]=%R op1[%#R]=%R rnd=%d", op2,op2,op1,op1,rnd_mode),
("r[%#R]=%R inexact=%d", r, r, inexact));
/* Deal with special values */
if (MPFR_ARE_SINGULAR (op1, op2))
{
/* If a or b is NaN, the result is NaN */
if (MPFR_IS_NAN(op1) || MPFR_IS_NAN(op2))
{
MPFR_SET_NAN(r);
MPFR_RET_NAN;
}
/* now one of a or b is Inf or 0 */
/* If a and b is +Inf, the result is +Inf.
Otherwise if a or b is -Inf or 0, the result is NaN */
else if (MPFR_IS_INF(op1) || MPFR_IS_INF(op2))
{
if (MPFR_IS_STRICTPOS(op1) && MPFR_IS_STRICTPOS(op2))
{
MPFR_SET_INF(r);
MPFR_SET_SAME_SIGN(r, op1);
MPFR_RET(0); /* exact */
}
else
{
MPFR_SET_NAN(r);
MPFR_RET_NAN;
}
}
else /* a and b are neither NaN nor Inf, and one is zero */
{ /* If a or b is 0, the result is +0 since a sqrt is positive */
MPFR_ASSERTD (MPFR_IS_ZERO (op1) || MPFR_IS_ZERO (op2));
MPFR_SET_POS (r);
MPFR_SET_ZERO (r);
MPFR_RET (0); /* exact */
}
}
MPFR_CLEAR_FLAGS (r);
/* If a or b is negative (excluding -Infinity), the result is NaN */
if (MPFR_UNLIKELY(MPFR_IS_NEG(op1) || MPFR_IS_NEG(op2)))
{
MPFR_SET_NAN(r);
MPFR_RET_NAN;
}
/* Precision of the following calculus */
q = MPFR_PREC(r);
p = q + MPFR_INT_CEIL_LOG2(q) + 15;
MPFR_ASSERTD (p >= 7); /* see algorithms.tex */
s = (p - 1) / BITS_PER_MP_LIMB + 1;
/* b (op2) and a (op1) are the 2 operands but we want b >= a */
compare = mpfr_cmp (op1, op2);
if (MPFR_UNLIKELY( compare == 0 ))
{
mpfr_set (r, op1, rnd_mode);
MPFR_RET (0); /* exact */
}
else if (compare > 0)
{
mpfr_srcptr t = op1;
op1 = op2;
op2 = t;
}
/* Now b(=op2) >= a (=op1) */
MPFR_TMP_MARK(marker);
/* Main loop */
MPFR_ZIV_INIT (loop, p);
for (;;)
{
mp_prec_t eq;
/* Init temporary vars */
MPFR_TMP_INIT (up, u, p, s);
MPFR_TMP_INIT (vp, v, p, s);
MPFR_TMP_INIT (tmpp, tmp, p, s);
/* Calculus of un and vn */
mpfr_mul (u, op1, op2, GMP_RNDN); /* Faster since PREC(op) < PREC(u) */
mpfr_sqrt (u, u, GMP_RNDN);
mpfr_add (v, op1, op2, GMP_RNDN); /* add with !=prec is still good*/
mpfr_div_2ui (v, v, 1, GMP_RNDN);
n = 1;
while (mpfr_cmp2 (u, v, &eq) != 0 && eq <= p - 2)
{
mpfr_add (tmp, u, v, GMP_RNDN);
mpfr_div_2ui (tmp, tmp, 1, GMP_RNDN);
/* See proof in algorithms.tex */
if (4*eq > p)
{
mpfr_t w;
/* tmp = U(k) */
mpfr_init2 (w, (p + 1) / 2);
mpfr_sub (w, v, u, GMP_RNDN); /* e = V(k-1)-U(k-1) */
mpfr_sqr (w, w, GMP_RNDN); /* e = e^2 */
mpfr_div_2ui (w, w, 4, GMP_RNDN); /* e*= (1/2)^2*1/4 */
mpfr_div (w, w, tmp, GMP_RNDN); /* 1/4*e^2/U(k) */
mpfr_sub (v, tmp, w, GMP_RNDN);
err = MPFR_GET_EXP (tmp) - MPFR_GET_EXP (v); /* 0 or 1 */
mpfr_clear (w);
break;
}
mpfr_mul (u, u, v, GMP_RNDN);
mpfr_sqrt (u, u, GMP_RNDN);
mpfr_swap (v, tmp);
n ++;
}
/* the error on v is bounded by (18n+51) ulps, or twice if there
was an exponent loss in the final subtraction */
err += MPFR_INT_CEIL_LOG2(18 * n + 51); /* 18n+51 should not overflow
since n is about log(p) */
/* we should have n+2 <= 2^(p/4) [see algorithms.tex] */
if (MPFR_LIKELY (MPFR_INT_CEIL_LOG2(n + 2) <= p / 4 &&
MPFR_CAN_ROUND (v, p - err, q, rnd_mode)))
break; /* Stop the loop */
/* Next iteration */
MPFR_ZIV_NEXT (loop, p);
s = (p - 1) / BITS_PER_MP_LIMB + 1;
}
MPFR_ZIV_FREE (loop);
/* Setting of the result */
inexact = mpfr_set (r, v, rnd_mode);
/* Let's clean */
MPFR_TMP_FREE(marker);
return inexact; /* agm(u,v) can be exact for u, v rational only for u=v.
Proof (due to Nicolas Brisebarre): it suffices to consider
u=1 and v<1. Then 1/AGM(1,v) = 2F1(1/2,1/2,1;1-v^2),
and a theorem due to G.V. Chudnovsky states that for x a
non-zero algebraic number with |x|<1, then
2F1(1/2,1/2,1;x) and 2F1(-1/2,1/2,1;x) are algebraically
independent over Q. */
}
/* (y, z) <- (sin(x), cos(x)), return value is 0 iff both results are exact */
int
mpfr_sin_cos (mpfr_ptr y, mpfr_ptr z, mpfr_srcptr x, mp_rnd_t rnd_mode)
{
int prec, m, ok, e, inexact, neg;
mpfr_t c, k;
if (MPFR_IS_NAN(x) || MPFR_IS_INF(x))
{
MPFR_SET_NAN(y);
MPFR_SET_NAN(z);
MPFR_RET_NAN;
}
if (MPFR_IS_ZERO(x))
{
MPFR_CLEAR_FLAGS(y);
MPFR_SET_ZERO(y);
MPFR_SET_SAME_SIGN(y, x);
mpfr_set_ui (z, 1, GMP_RNDN);
MPFR_RET(0);
}
prec = MAX(MPFR_PREC(y), MPFR_PREC(z));
m = prec + _mpfr_ceil_log2 ((double) prec) + ABS(MPFR_EXP(x)) + 13;
mpfr_init2 (c, m);
mpfr_init2 (k, m);
/* first determine sign */
mpfr_const_pi (c, GMP_RNDN);
mpfr_mul_2ui (c, c, 1, GMP_RNDN); /* 2*Pi */
mpfr_div (k, x, c, GMP_RNDN); /* x/(2*Pi) */
mpfr_floor (k, k); /* floor(x/(2*Pi)) */
mpfr_mul (c, k, c, GMP_RNDN);
mpfr_sub (k, x, c, GMP_RNDN); /* 0 <= k < 2*Pi */
mpfr_const_pi (c, GMP_RNDN); /* cached */
neg = mpfr_cmp (k, c) > 0;
mpfr_clear (k);
do
{
mpfr_cos (c, x, GMP_RNDZ);
if ((ok = mpfr_can_round (c, m, GMP_RNDZ, rnd_mode, MPFR_PREC(z))))
{
inexact = mpfr_set (z, c, rnd_mode);
mpfr_mul (c, c, c, GMP_RNDU);
mpfr_ui_sub (c, 1, c, GMP_RNDN);
e = 2 + (-MPFR_EXP(c)) / 2;
mpfr_sqrt (c, c, GMP_RNDN);
if (neg)
mpfr_neg (c, c, GMP_RNDN);
/* the absolute error on c is at most 2^(e-m) = 2^(EXP(c)-err) */
e = MPFR_EXP(c) + m - e;
ok = (e >= 0) && mpfr_can_round (c, e, GMP_RNDN, rnd_mode,
MPFR_PREC(y));
}
if (ok == 0)
{
m += _mpfr_ceil_log2 ((double) m);
mpfr_set_prec (c, m);
}
}
while (ok == 0);
inexact = mpfr_set (y, c, rnd_mode) || inexact;
mpfr_clear (c);
return inexact; /* inexact */
}
/* returns 0 if result exact, non-zero otherwise */
int
mpfr_div_ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int u, mp_rnd_t rnd_mode)
{
long int xn, yn, dif, sh, i;
mp_limb_t *xp, *yp, *tmp, c, d;
mp_exp_t exp;
int inexact, middle = 1;
TMP_DECL(marker);
if (MPFR_UNLIKELY( MPFR_IS_SINGULAR(x) ))
{
if (MPFR_IS_NAN(x))
{
MPFR_SET_NAN(y);
MPFR_RET_NAN;
}
else if (MPFR_IS_INF(x))
{
MPFR_SET_INF(y);
MPFR_SET_SAME_SIGN(y, x);
MPFR_RET(0);
}
else
{
MPFR_ASSERTD(MPFR_IS_ZERO(x));
if (u == 0)/* 0/0 is NaN */
{
MPFR_SET_NAN(y);
MPFR_RET_NAN;
}
else
{
MPFR_SET_ZERO(y);
MPFR_RET(0);
}
}
}
if (MPFR_UNLIKELY(u == 0))
{
/* x/0 is Inf */
MPFR_SET_INF(y);
MPFR_SET_SAME_SIGN(y, x);
MPFR_RET(0);
}
MPFR_CLEAR_FLAGS(y);
MPFR_SET_SAME_SIGN(y, x);
TMP_MARK(marker);
xn = MPFR_LIMB_SIZE(x);
yn = MPFR_LIMB_SIZE(y);
xp = MPFR_MANT(x);
yp = MPFR_MANT(y);
exp = MPFR_GET_EXP (x);
dif = yn + 1 - xn;
/* we need to store yn+1 = xn + dif limbs of the quotient */
/* don't use tmp=yp since the mpn_lshift call below requires yp >= tmp+1 */
tmp = (mp_limb_t*) TMP_ALLOC((yn + 1) * BYTES_PER_MP_LIMB);
c = (mp_limb_t) u;
MPFR_ASSERTN(u == c);
if (dif >= 0)
c = mpn_divrem_1 (tmp, dif, xp, xn, c); /* used all the dividend */
else /* dif < 0 i.e. xn > yn, don't use the (-dif) low limbs from x */
c = mpn_divrem_1 (tmp, 0, xp - dif, yn + 1, c);
inexact = (c != 0);
/* First pass in estimating next bit of the quotient, in case of RNDN *
* In case we just have the right number of bits (postpone this ?), *
* we need to check whether the remainder is more or less than half *
* the divisor. The test must be performed with a subtraction, so as *
* to prevent carries. */
if (rnd_mode == GMP_RNDN)
{
if (c < (mp_limb_t) u - c) /* We have u > c */
middle = -1;
else if (c > (mp_limb_t) u - c)
middle = 1;
else
middle = 0; /* exactly in the middle */
}
/* If we believe that we are right in the middle or exact, we should check
that we did not neglect any word of x (division large / 1 -> small). */
for (i=0; ((inexact == 0) || (middle == 0)) && (i < -dif); i++)
if (xp[i])
inexact = middle = 1; /* larger than middle */
/*
If the high limb of the result is 0 (xp[xn-1] < u), remove it.
Otherwise, compute the left shift to be performed to normalize.
In the latter case, we discard some low bits computed. They
contain information useful for the rounding, hence the updating
of middle and inexact.
*/
if (tmp[yn] == 0)
{
MPN_COPY(yp, tmp, yn);
exp -= BITS_PER_MP_LIMB;
sh = 0;
}
else
{
count_leading_zeros (sh, tmp[yn]);
/* shift left to normalize */
if (sh)
{
mp_limb_t w = tmp[0] << sh;
mpn_lshift (yp, tmp + 1, yn, sh);
yp[0] += tmp[0] >> (BITS_PER_MP_LIMB - sh);
if (w > (MPFR_LIMB_ONE << (BITS_PER_MP_LIMB - 1)))
{ middle = 1; }
else if (w < (MPFR_LIMB_ONE << (BITS_PER_MP_LIMB - 1)))
{ middle = -1; }
else
{ middle = (c != 0); }
inexact = inexact || (w != 0);
exp -= sh;
}
else
{ /* this happens only if u == 1 and xp[xn-1] >=
1<<(BITS_PER_MP_LIMB-1). It might be better to handle the
u == 1 case seperately ?
*/
MPN_COPY (yp, tmp + 1, yn);
}
}
/* The computation of z = pow(x,y) is done by
z = exp(y * log(x)) = x^y */
int
mpfr_pow (mpfr_ptr z, mpfr_srcptr x, mpfr_srcptr y, mp_rnd_t rnd_mode)
{
int inexact = 0;
if (MPFR_IS_NAN(x) || MPFR_IS_NAN(y))
{
MPFR_SET_NAN(z);
MPFR_RET_NAN;
}
if (MPFR_IS_INF(y))
{
mpfr_t one;
int cmp;
if (MPFR_SIGN(y) > 0)
{
if (MPFR_IS_INF(x))
{
MPFR_CLEAR_FLAGS(z);
if (MPFR_SIGN(x) > 0)
MPFR_SET_INF(z);
else
MPFR_SET_ZERO(z);
MPFR_SET_POS(z);
MPFR_RET(0);
}
MPFR_CLEAR_FLAGS(z);
if (MPFR_IS_ZERO(x))
{
MPFR_SET_ZERO(z);
MPFR_SET_POS(z);
MPFR_RET(0);
}
mpfr_init2(one, BITS_PER_MP_LIMB);
mpfr_set_ui(one, 1, GMP_RNDN);
cmp = mpfr_cmp_abs(x, one);
mpfr_clear(one);
if (cmp > 0)
{
MPFR_SET_INF(z);
MPFR_SET_POS(z);
MPFR_RET(0);
}
else if (cmp < 0)
{
MPFR_SET_ZERO(z);
MPFR_SET_POS(z);
MPFR_RET(0);
}
else
{
MPFR_SET_NAN(z);
MPFR_RET_NAN;
}
}
else
{
if (MPFR_IS_INF(x))
{
MPFR_CLEAR_FLAGS(z);
if (MPFR_SIGN(x) > 0)
MPFR_SET_ZERO(z);
else
MPFR_SET_INF(z);
MPFR_SET_POS(z);
MPFR_RET(0);
}
if (MPFR_IS_ZERO(x))
{
MPFR_SET_INF(z);
MPFR_SET_POS(z);
MPFR_RET(0);
}
mpfr_init2(one, BITS_PER_MP_LIMB);
mpfr_set_ui(one, 1, GMP_RNDN);
cmp = mpfr_cmp_abs(x, one);
mpfr_clear(one);
MPFR_CLEAR_FLAGS(z);
if (cmp > 0)
{
MPFR_SET_ZERO(z);
MPFR_SET_POS(z);
MPFR_RET(0);
}
else if (cmp < 0)
{
MPFR_SET_INF(z);
MPFR_SET_POS(z);
MPFR_RET(0);
}
else
{
MPFR_SET_NAN(z);
MPFR_RET_NAN;
}
}
}
if (MPFR_IS_ZERO(y))
{
return mpfr_set_ui (z, 1, GMP_RNDN);
}
if (mpfr_isinteger (y))
{
mpz_t zi;
long int zii;
int exptol;
mpz_init(zi);
exptol = mpfr_get_z_exp (zi, y);
if (exptol>0)
mpz_mul_2exp(zi, zi, exptol);
else
mpz_tdiv_q_2exp(zi, zi, (unsigned long int) (-exptol));
zii=mpz_get_ui(zi);
mpz_clear(zi);
return mpfr_pow_si (z, x, zii, rnd_mode);
}
if (MPFR_IS_INF(x))
{
if (MPFR_SIGN(x) > 0)
{
MPFR_CLEAR_FLAGS(z);
if (MPFR_SIGN(y) > 0)
MPFR_SET_INF(z);
else
MPFR_SET_ZERO(z);
MPFR_SET_POS(z);
MPFR_RET(0);
}
else
{
MPFR_SET_NAN(z);
MPFR_RET_NAN;
}
}
if (MPFR_IS_ZERO(x))
{
MPFR_CLEAR_FLAGS(z);
MPFR_SET_ZERO(z);
MPFR_SET_SAME_SIGN(z, x);
MPFR_RET(0);
}
if (MPFR_SIGN(x) < 0)
{
MPFR_SET_NAN(z);
MPFR_RET_NAN;
}
MPFR_CLEAR_FLAGS(z);
/* General case */
{
/* Declaration of the intermediary variable */
mpfr_t t, te, ti;
int loop = 0, ok;
/* Declaration of the size variable */
mp_prec_t Nx = MPFR_PREC(x); /* Precision of input variable */
mp_prec_t Ny = MPFR_PREC(y); /* Precision of input variable */
mp_prec_t Nt; /* Precision of the intermediary variable */
long int err; /* Precision of error */
/* compute the precision of intermediary variable */
Nt=MAX(Nx,Ny);
/* the optimal number of bits : see algorithms.ps */
Nt=Nt+5+_mpfr_ceil_log2(Nt);
/* initialise of intermediary variable */
mpfr_init(t);
mpfr_init(ti);
mpfr_init(te);
do
{
loop ++;
/* reactualisation of the precision */
mpfr_set_prec (t, Nt);
mpfr_set_prec (ti, Nt);
mpfr_set_prec (te, Nt);
/* compute exp(y*ln(x)) */
mpfr_log (ti, x, GMP_RNDU); /* ln(n) */
mpfr_mul (te, y, ti, GMP_RNDU); /* y*ln(n) */
mpfr_exp (t, te, GMP_RNDN); /* exp(x*ln(n))*/
/* estimation of the error -- see pow function in algorithms.ps*/
err = Nt - (MPFR_EXP(te) + 3);
/* actualisation of the precision */
Nt += 10;
ok = mpfr_can_round (t, err, GMP_RNDN, rnd_mode, Ny);
/* check exact power */
if (ok == 0 && loop == 1)
ok = mpfr_pow_is_exact (x, y);
}
while (err < 0 || ok == 0);
inexact = mpfr_set (z, t, rnd_mode);
mpfr_clear (t);
mpfr_clear (ti);
mpfr_clear (te);
}
return inexact;
}
