int
mpfr_ui_div (mpfr_ptr y, unsigned long int u, mpfr_srcptr x, mpfr_rnd_t rnd_mode)
{
mpfr_t uu;
mp_limb_t up[1];
unsigned long cnt;
MPFR_LOG_FUNC
(("u=%lu x[%Pu]=%.*Rg rnd=%d",
u, mpfr_get_prec(x), mpfr_log_prec, x, rnd_mode),
("y[%Pu]=%.*Rg", mpfr_get_prec(y), mpfr_log_prec, y));
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)) /* u/Inf = 0 */
{
MPFR_SET_ZERO(y);
MPFR_SET_SAME_SIGN(y,x);
MPFR_RET(0);
}
else /* u / 0 */
{
MPFR_ASSERTD(MPFR_IS_ZERO(x));
if (u)
{
/* u > 0, so y = sign(x) * Inf */
MPFR_SET_SAME_SIGN(y, x);
MPFR_SET_INF(y);
mpfr_set_divby0 ();
MPFR_RET(0);
}
else
{
/* 0 / 0 */
MPFR_SET_NAN(y);
MPFR_RET_NAN;
}
}
}
else if (MPFR_LIKELY(u != 0))
{
MPFR_TMP_INIT1(up, uu, GMP_NUMB_BITS);
MPFR_ASSERTN(u == (mp_limb_t) u);
count_leading_zeros(cnt, (mp_limb_t) u);
up[0] = (mp_limb_t) u << cnt;
MPFR_SET_EXP (uu, GMP_NUMB_BITS - cnt);
return mpfr_div (y, uu, x, rnd_mode);
}
else /* u = 0, and x != 0 */
{
MPFR_SET_ZERO(y); /* if u=0, then set y to 0 */
MPFR_SET_SAME_SIGN(y, x); /* u considered as +0: sign(+0/x) = sign(x) */
MPFR_RET(0);
}
}
int
mpfr_ui_div (mpfr_ptr y, unsigned long int u, mpfr_srcptr x, mp_rnd_t rnd_mode)
{
mpfr_t uu;
mp_limb_t up[1];
unsigned long cnt;
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)) /* u/Inf = 0 */
{
MPFR_SET_ZERO(y);
MPFR_SET_SAME_SIGN(y,x);
MPFR_RET(0);
}
else /* u / 0 */
{
MPFR_ASSERTD(MPFR_IS_ZERO(x));
if (u)
{
/* u > 0, so y = sign(x) * Inf */
MPFR_SET_SAME_SIGN(y, x);
MPFR_SET_INF(y);
MPFR_RET(0);
}
else
{
/* 0 / 0 */
MPFR_SET_NAN(y);
MPFR_RET_NAN;
}
}
}
else if (MPFR_LIKELY(u != 0))
{
MPFR_TMP_INIT1(up, uu, BITS_PER_MP_LIMB);
MPFR_ASSERTN(u == (mp_limb_t) u);
count_leading_zeros(cnt, (mp_limb_t) u);
up[0] = (mp_limb_t) u << cnt;
MPFR_SET_EXP (uu, BITS_PER_MP_LIMB - cnt);
return mpfr_div (y, uu, x, rnd_mode);
}
else /* u = 0, and x != 0 */
{
MPFR_SET_ZERO(y); /* if u=0, then set y to 0 */
MPFR_SET_SAME_SIGN(y, x); /* u considered as +0: sign(+0/x) = sign(x) */
MPFR_RET(0);
}
}
int
mpfr_root (mpfr_ptr y, mpfr_srcptr x, unsigned long k, mpfr_rnd_t rnd_mode)
{
mpz_t m;
mpfr_exp_t e, r, sh;
mpfr_prec_t n, size_m, tmp;
int inexact, negative;
MPFR_SAVE_EXPO_DECL (expo);
MPFR_LOG_FUNC
(("x[%Pu]=%.*Rg k=%lu rnd=%d",
mpfr_get_prec (x), mpfr_log_prec, x, k, rnd_mode),
("y[%Pu]=%.*Rg inexact=%d",
mpfr_get_prec (y), mpfr_log_prec, y, inexact));
if (MPFR_UNLIKELY (k <= 1))
{
if (k < 1) /* k==0 => y=x^(1/0)=x^(+Inf) */
#if 0
/* For 0 <= x < 1 => +0.
For x = 1 => 1.
For x > 1, => +Inf.
For x < 0 => NaN.
*/
{
if (MPFR_IS_NEG (x) && !MPFR_IS_ZERO (x))
{
MPFR_SET_NAN (y);
MPFR_RET_NAN;
}
inexact = mpfr_cmp (x, __gmpfr_one);
if (inexact == 0)
return mpfr_set_ui (y, 1, rnd_mode); /* 1 may be Out of Range */
else if (inexact < 0)
return mpfr_set_ui (y, 0, rnd_mode); /* 0+ */
else
{
mpfr_set_inf (y, 1);
return 0;
}
}
#endif
{
MPFR_SET_NAN (y);
MPFR_RET_NAN;
}
else /* y =x^(1/1)=x */
return mpfr_set (y, x, rnd_mode);
}
/* reldiff(b, c) = abs(b-c)/b */
void
mpfr_reldiff (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode)
{
mpfr_t b_copy;
if (MPFR_ARE_SINGULAR (b, c))
{
if (MPFR_IS_NAN(b) || MPFR_IS_NAN(c))
{
MPFR_SET_NAN(a);
return;
}
else if (MPFR_IS_INF(b))
{
if (MPFR_IS_INF (c) && (MPFR_SIGN (c) == MPFR_SIGN (b)))
MPFR_SET_ZERO(a);
else
MPFR_SET_NAN(a);
return;
}
else if (MPFR_IS_INF(c))
{
MPFR_SET_SAME_SIGN (a, b);
MPFR_SET_INF (a);
return;
}
else if (MPFR_IS_ZERO(b)) /* reldiff = abs(c)/c = sign(c) */
{
mpfr_set_si (a, MPFR_INT_SIGN (c), rnd_mode);
return;
}
/* Fall through */
}
if (a == b)
{
mpfr_init2 (b_copy, MPFR_PREC(b));
mpfr_set (b_copy, b, MPFR_RNDN);
}
mpfr_sub (a, b, c, rnd_mode);
mpfr_abs (a, a, rnd_mode); /* for compatibility with MPF */
mpfr_div (a, a, (a == b) ? b_copy : b, rnd_mode);
if (a == b)
mpfr_clear (b_copy);
}
int
mpfr_frexp (mpfr_exp_t *exp, mpfr_ptr y, mpfr_srcptr x, mpfr_rnd_t rnd)
{
int inex;
if (MPFR_UNLIKELY(MPFR_IS_SINGULAR(x)))
{
if (MPFR_IS_NAN(x))
{
MPFR_SET_NAN(y);
MPFR_RET_NAN; /* exp is unspecified */
}
else if (MPFR_IS_INF(x))
{
MPFR_SET_INF(y);
MPFR_SET_SAME_SIGN(y,x);
MPFR_RET(0); /* exp is unspecified */
}
else
{
MPFR_SET_ZERO(y);
MPFR_SET_SAME_SIGN(y,x);
*exp = 0;
MPFR_RET(0);
}
}
inex = mpfr_set (y, x, rnd);
*exp = MPFR_GET_EXP (y);
MPFR_SET_EXP (y, 0);
return mpfr_check_range (y, inex, rnd);
}
int
mpfr_urandomb (mpfr_ptr rop, gmp_randstate_t rstate)
{
mp_ptr rp;
mp_prec_t nbits;
mp_size_t nlimbs;
mp_size_t k; /* number of high zero limbs */
mp_exp_t exp;
int cnt;
MPFR_CLEAR_FLAGS (rop);
rp = MPFR_MANT (rop);
nbits = MPFR_PREC (rop);
nlimbs = MPFR_LIMB_SIZE (rop);
MPFR_SET_POS (rop);
/* Uniform non-normalized significand */
_gmp_rand (rp, rstate, nlimbs * BITS_PER_MP_LIMB);
/* If nbits isn't a multiple of BITS_PER_MP_LIMB, mask the low bits */
cnt = nlimbs * BITS_PER_MP_LIMB - nbits;
if (MPFR_LIKELY (cnt != 0))
rp[0] &= ~MPFR_LIMB_MASK (cnt);
/* Count the null significant limbs and remaining limbs */
exp = 0;
k = 0;
while (nlimbs != 0 && rp[nlimbs - 1] == 0)
{
k ++;
nlimbs --;
exp -= BITS_PER_MP_LIMB;
}
if (MPFR_LIKELY (nlimbs != 0)) /* otherwise value is zero */
{
count_leading_zeros (cnt, rp[nlimbs - 1]);
/* Normalization */
if (mpfr_set_exp (rop, exp - cnt))
{
/* If the exponent is not in the current exponent range, we
choose to return a NaN as this is probably a user error.
Indeed this can happen only if the exponent range has been
reduced to a very small interval and/or the precision is
huge (very unlikely). */
MPFR_SET_NAN (rop);
__gmpfr_flags |= MPFR_FLAGS_NAN; /* Can't use MPFR_RET_NAN */
return 1;
}
if (cnt != 0)
mpn_lshift (rp + k, rp, nlimbs, cnt);
if (k != 0)
MPN_ZERO (rp, k);
}
else
MPFR_SET_ZERO (rop);
return 0;
}
/* compute remainder as in definition:
r = x - n * y, where n = trunc(x/y).
warning: may change flags. */
static int
slow_fmod (mpfr_ptr r, mpfr_srcptr x, mpfr_srcptr y, mpfr_rnd_t rnd)
{
mpfr_t q;
int inexact;
if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x) || MPFR_IS_SINGULAR (y)))
{
if (MPFR_IS_NAN (x) || MPFR_IS_NAN (y) || MPFR_IS_INF (x)
|| MPFR_IS_ZERO (y))
{
MPFR_SET_NAN (r);
MPFR_RET_NAN;
}
else /* either y is Inf and x is 0 or non-special,
or x is 0 and y is non-special,
in both cases the quotient is zero. */
return mpfr_set (r, x, rnd);
}
/* regular cases */
/* if 2^(ex-1) <= |x| < 2^ex, and 2^(ey-1) <= |y| < 2^ey,
then |x/y| < 2^(ex-ey+1) */
mpfr_init2 (q,
MAX (MPFR_PREC_MIN, mpfr_get_exp (x) - mpfr_get_exp (y) + 1));
mpfr_div (q, x, y, MPFR_RNDZ);
mpfr_trunc (q, q); /* may change inexact flag */
mpfr_prec_round (q, mpfr_get_prec (q) + mpfr_get_prec (y), MPFR_RNDZ);
inexact = mpfr_mul (q, q, y, MPFR_RNDZ); /* exact */
inexact = mpfr_sub (r, x, q, rnd);
mpfr_clear (q);
return inexact;
}
int
mpfr_max (mpfr_ptr z, mpfr_srcptr x, mpfr_srcptr y, mp_rnd_t rnd_mode)
{
if (MPFR_IS_NAN(x) && MPFR_IS_NAN(y) )
{
MPFR_SET_NAN(z);
MPFR_RET_NAN;
}
MPFR_CLEAR_NAN(z);
if (MPFR_IS_NAN(x))
return mpfr_set(z, y, rnd_mode);
if (MPFR_IS_NAN(y))
return mpfr_set(z, x, rnd_mode);
if (MPFR_IS_FP(x) && MPFR_IS_ZERO(x) && MPFR_IS_FP(y) && MPFR_IS_ZERO(y))
{
if (MPFR_SIGN(x) < 0)
return mpfr_set(z, y, rnd_mode);
else
return mpfr_set(z, x, rnd_mode);
}
if (mpfr_cmp(x,y) <= 0)
return mpfr_set(z, y, rnd_mode);
else
return mpfr_set(z, x, rnd_mode);
}
int
mpfr_max (mpfr_ptr z, mpfr_srcptr x, mpfr_srcptr y, mpfr_rnd_t rnd_mode)
{
if (MPFR_ARE_SINGULAR(x,y))
{
if (MPFR_IS_NAN(x) && MPFR_IS_NAN(y) )
{
MPFR_SET_NAN(z);
MPFR_RET_NAN;
}
else if (MPFR_IS_NAN(x))
return mpfr_set(z, y, rnd_mode);
else if (MPFR_IS_NAN(y))
return mpfr_set(z, x, rnd_mode);
else if (MPFR_IS_ZERO(x) && MPFR_IS_ZERO(y))
{
if (MPFR_IS_NEG(x))
return mpfr_set(z, y, rnd_mode);
else
return mpfr_set(z, x, rnd_mode);
}
}
if (mpfr_cmp(x,y) <= 0)
return mpfr_set(z, y, rnd_mode);
else
return mpfr_set(z, x, rnd_mode);
}
void
mpfr_set_str_binary (mpfr_ptr x, const char *str)
{
int has_sign;
int res;
if (*str == 'N')
{
MPFR_SET_NAN(x);
__gmpfr_flags |= MPFR_FLAGS_NAN;
return;
}
has_sign = *str == '-' || *str == '+';
if (str[has_sign] == 'I')
{
MPFR_SET_INF(x);
if (*str == '-')
MPFR_SET_NEG(x);
else
MPFR_SET_POS(x);
return;
}
res = mpfr_strtofr (x, str, 0, 2, MPFR_RNDZ);
MPFR_ASSERTN (res == 0);
}
/* set f to the rational q */
int
mpfr_set_q (mpfr_ptr f, mpq_srcptr q, mp_rnd_t rnd)
{
mpz_srcptr num, den;
mpfr_t n, d;
int inexact;
mp_prec_t prec;
MPFR_CLEAR_FLAGS (f);
num = mpq_numref (q);
if (mpz_cmp_ui (num, 0) == 0)
{
MPFR_SET_ZERO (f);
MPFR_SET_POS (f);
MPFR_RET (0);
}
den = mpq_denref (q);
mpfr_save_emin_emax ();
prec = mpz_sizeinbase (num, 2);
if (prec < MPFR_PREC_MIN)
prec = MPFR_PREC_MIN;
mpfr_init2 (n, prec);
if (mpfr_set_z (n, num, GMP_RNDZ)) /* result is exact unless overflow */
{
mpfr_clear (n);
mpfr_restore_emin_emax ();
MPFR_SET_NAN (f);
MPFR_RET_NAN;
}
prec = mpz_sizeinbase(den, 2);
if (prec < MPFR_PREC_MIN)
prec = MPFR_PREC_MIN;
mpfr_init2 (d, prec);
if (mpfr_set_z (d, den, GMP_RNDZ)) /* result is exact unless overflow */
{
mpfr_clear (d);
mpfr_clear (n);
mpfr_restore_emin_emax ();
MPFR_SET_NAN (f);
MPFR_RET_NAN;
}
inexact = mpfr_div (f, n, d, rnd);
mpfr_clear (n);
mpfr_clear (d);
MPFR_RESTORE_RET (inexact, f, rnd);
}
int
mpfr_urandomb (mpfr_ptr rop, gmp_randstate_t rstate)
{
mpfr_limb_ptr rp;
mpfr_prec_t nbits;
mp_size_t nlimbs;
mp_size_t k; /* number of high zero limbs */
mpfr_exp_t exp;
int cnt;
rp = MPFR_MANT (rop);
nbits = MPFR_PREC (rop);
nlimbs = MPFR_LIMB_SIZE (rop);
MPFR_SET_POS (rop);
cnt = nlimbs * GMP_NUMB_BITS - nbits;
/* Uniform non-normalized significand */
/* generate exactly nbits so that the random generator stays in the same
state, independent of the machine word size GMP_NUMB_BITS */
mpfr_rand_raw (rp, rstate, nbits);
if (MPFR_LIKELY (cnt != 0)) /* this will put the low bits to zero */
mpn_lshift (rp, rp, nlimbs, cnt);
/* Count the null significant limbs and remaining limbs */
exp = 0;
k = 0;
while (nlimbs != 0 && rp[nlimbs - 1] == 0)
{
k ++;
nlimbs --;
exp -= GMP_NUMB_BITS;
}
if (MPFR_LIKELY (nlimbs != 0)) /* otherwise value is zero */
{
count_leading_zeros (cnt, rp[nlimbs - 1]);
/* Normalization */
if (mpfr_set_exp (rop, exp - cnt))
{
/* If the exponent is not in the current exponent range, we
choose to return a NaN as this is probably a user error.
Indeed this can happen only if the exponent range has been
reduced to a very small interval and/or the precision is
huge (very unlikely). */
MPFR_SET_NAN (rop);
__gmpfr_flags |= MPFR_FLAGS_NAN; /* Can't use MPFR_RET_NAN */
return 1;
}
if (cnt != 0)
mpn_lshift (rp + k, rp, nlimbs, cnt);
if (k != 0)
MPN_ZERO (rp, k);
}
else
MPFR_SET_ZERO (rop);
return 0;
}
static void
check_nan (void)
{
mpfr_t d, q;
mpfr_init2 (d, 100L);
mpfr_init2 (q, 100L);
/* 1/+inf == 0 */
MPFR_CLEAR_FLAGS (d);
MPFR_SET_INF (d);
MPFR_SET_POS (d);
MPFR_ASSERTN (mpfr_ui_div (q, 1L, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_number_p (q));
MPFR_ASSERTN (mpfr_sgn (q) == 0);
/* 1/-inf == -0 */
MPFR_CLEAR_FLAGS (d);
MPFR_SET_INF (d);
MPFR_SET_NEG (d);
MPFR_ASSERTN (mpfr_ui_div (q, 1L, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_number_p (q));
MPFR_ASSERTN (mpfr_sgn (q) == 0);
/* 1/nan == nan */
MPFR_SET_NAN (d);
MPFR_ASSERTN (mpfr_ui_div (q, 1L, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_nan_p (q));
/* 0/0 == nan */
mpfr_set_ui (d, 0L, GMP_RNDN);
MPFR_ASSERTN (mpfr_ui_div (q, 0L, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_nan_p (q));
/* 1/+0 = +inf */
mpfr_set_ui (d, 0L, GMP_RNDN);
MPFR_ASSERTN (mpfr_ui_div (q, 1L, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_inf_p (q) && mpfr_sgn (q) > 0);
/* 1/-0 = -inf */
mpfr_set_ui (d, 0L, GMP_RNDN);
mpfr_neg (d, d, GMP_RNDN);
MPFR_ASSERTN (mpfr_ui_div (q, 1L, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_inf_p (q) && mpfr_sgn (q) < 0);
/* 0/1 = +0 */
mpfr_set_ui (d, 1L, GMP_RNDN);
MPFR_ASSERTN (mpfr_ui_div (q, 0L, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_cmp_ui (q, 0) == 0 && MPFR_IS_POS (q));
/* 0/-1 = -0 */
mpfr_set_si (d, -1, GMP_RNDN);
MPFR_ASSERTN (mpfr_ui_div (q, 0L, d, GMP_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_cmp_ui (q, 0) == 0 && MPFR_IS_NEG (q));
mpfr_clear (d);
mpfr_clear (q);
}
/* Maybe better create its own test file ? */
static void
check_neg_special (void)
{
mpfr_t x;
mpfr_init (x);
MPFR_SET_NAN (x);
mpfr_clear_nanflag ();
mpfr_neg (x, x, MPFR_RNDN);
PRINT_ERROR_IF (!mpfr_nanflag_p (),
"ERROR: neg (NaN) doesn't set Nan flag.\n");
mpfr_clear (x);
}
static void
set_special (mpfr_ptr x, unsigned int select)
{
MPFR_ASSERTN (select < SPECIAL_MAX);
switch (select)
{
case 0:
MPFR_SET_NAN (x);
break;
case 1:
MPFR_SET_INF (x);
MPFR_SET_POS (x);
break;
case 2:
MPFR_SET_INF (x);
MPFR_SET_NEG (x);
break;
case 3:
MPFR_SET_ZERO (x);
MPFR_SET_POS (x);
break;
case 4:
MPFR_SET_ZERO (x);
MPFR_SET_NEG (x);
break;
case 5:
mpfr_set_str_binary (x, "1");
break;
case 6:
mpfr_set_str_binary (x, "-1");
break;
case 7:
mpfr_set_str_binary (x, "1e-1");
break;
case 8:
mpfr_set_str_binary (x, "1e+1");
break;
case 9:
mpfr_const_pi (x, MPFR_RNDN);
break;
case 10:
mpfr_const_pi (x, MPFR_RNDN);
MPFR_SET_EXP (x, MPFR_GET_EXP (x)-1);
break;
default:
mpfr_urandomb (x, RANDS);
if (randlimb () & 1)
mpfr_neg (x, x, MPFR_RNDN);
break;
}
}
static void
check_flags (void)
{
mpfr_t x;
mpfr_exp_t old_emin, old_emax;
old_emin = mpfr_get_emin ();
old_emax = mpfr_get_emax ();
mpfr_init (x);
/* Check the functions not the macros ! */
(mpfr_clear_flags)();
mpfr_set_double_range ();
mpfr_set_ui (x, 1, MPFR_RNDN);
(mpfr_clear_overflow)();
mpfr_mul_2exp (x, x, 1024, MPFR_RNDN);
if (!(mpfr_overflow_p)())
ERROR("ERROR: No overflow detected!\n");
(mpfr_clear_underflow)();
mpfr_set_ui (x, 1, MPFR_RNDN);
mpfr_div_2exp (x, x, 1025, MPFR_RNDN);
if (!(mpfr_underflow_p)())
ERROR("ERROR: No underflow detected!\n");
(mpfr_clear_nanflag)();
MPFR_SET_NAN(x);
mpfr_add (x, x, x, MPFR_RNDN);
if (!(mpfr_nanflag_p)())
ERROR("ERROR: No NaN flag!\n");
(mpfr_clear_inexflag)();
mpfr_set_ui(x, 2, MPFR_RNDN);
mpfr_cos(x, x, MPFR_RNDN);
if (!(mpfr_inexflag_p)())
ERROR("ERROR: No inexact flag!\n");
(mpfr_clear_erangeflag) ();
mpfr_set_ui (x, 1, MPFR_RNDN);
mpfr_mul_2exp (x, x, 1024, MPFR_RNDN);
mpfr_get_ui (x, MPFR_RNDN);
if (!(mpfr_erangeflag_p)())
ERROR ("ERROR: No erange flag!\n");
mpfr_clear (x);
set_emin (old_emin);
set_emax (old_emax);
}
/* Maybe better create its own test file ? */
static void
check_neg_special ()
{
mpfr_t x;
mpfr_init (x);
MPFR_SET_NAN (x);
mpfr_clear_nanflag ();
mpfr_neg (x, x, GMP_RNDN);
if (!mpfr_nanflag_p () )
{
printf("ERROR: neg (NaN) doesn't set Nan flag.\n");
exit (1);
}
mpfr_clear (x);
}
static void
check_singular (void)
{
mpfr_t x, got;
mpfr_init2 (x, 100L);
mpfr_init2 (got, 100L);
/* sqrt(NaN) == NaN */
MPFR_SET_NAN (x);
MPFR_ASSERTN (test_sqrt (got, x, MPFR_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_nan_p (got));
/* sqrt(-1) == NaN */
mpfr_set_si (x, -1L, MPFR_RNDZ);
MPFR_ASSERTN (test_sqrt (got, x, MPFR_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_nan_p (got));
/* sqrt(+inf) == +inf */
MPFR_SET_INF (x);
MPFR_SET_POS (x);
MPFR_ASSERTN (test_sqrt (got, x, MPFR_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_inf_p (got));
/* sqrt(-inf) == NaN */
MPFR_SET_INF (x);
MPFR_SET_NEG (x);
MPFR_ASSERTN (test_sqrt (got, x, MPFR_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_nan_p (got));
/* sqrt(+0) == +0 */
mpfr_set_si (x, 0L, MPFR_RNDZ);
MPFR_ASSERTN (test_sqrt (got, x, MPFR_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_number_p (got));
MPFR_ASSERTN (mpfr_cmp_ui (got, 0L) == 0);
MPFR_ASSERTN (MPFR_IS_POS (got));
/* sqrt(-0) == -0 */
mpfr_set_si (x, 0L, MPFR_RNDZ);
MPFR_SET_NEG (x);
MPFR_ASSERTN (test_sqrt (got, x, MPFR_RNDZ) == 0); /* exact */
MPFR_ASSERTN (mpfr_number_p (got));
MPFR_ASSERTN (mpfr_cmp_ui (got, 0L) == 0);
MPFR_ASSERTN (MPFR_IS_NEG (got));
mpfr_clear (x);
mpfr_clear (got);
}
int
mpfr_dim (mpfr_ptr z, mpfr_srcptr x, mpfr_srcptr y, mpfr_rnd_t rnd_mode)
{
if (MPFR_IS_NAN(x) || MPFR_IS_NAN(y))
{
MPFR_SET_NAN(z);
MPFR_RET_NAN;
}
if (mpfr_cmp (x,y) > 0)
return mpfr_sub (z, x, y, rnd_mode);
else
{
MPFR_SET_ZERO(z);
MPFR_SET_POS(z);
MPFR_RET(0);
}
}
static void
check_special (void)
{
mpfr_t x;
int ret = 0;
mpfr_init (x);
MPFR_SET_ZERO (x);
if ((mpfr_sgn) (x) != 0 || mpfr_sgn (x) != 0)
{
printf("Sgn error for 0.\n");
ret = 1;
}
MPFR_SET_INF (x);
MPFR_SET_POS (x);
if ((mpfr_sgn) (x) != 1 || mpfr_sgn (x) != 1)
{
printf("Sgn error for +Inf.\n");
ret = 1;
}
MPFR_SET_INF (x);
MPFR_SET_NEG (x);
if ((mpfr_sgn) (x) != -1 || mpfr_sgn (x) != -1)
{
printf("Sgn error for -Inf.\n");
ret = 1;
}
MPFR_SET_NAN (x);
mpfr_clear_flags ();
if ((mpfr_sgn) (x) != 0 || !mpfr_erangeflag_p ())
{
printf("Sgn error for NaN.\n");
ret = 1;
}
mpfr_clear_flags ();
if (mpfr_sgn (x) != 0 || !mpfr_erangeflag_p ())
{
printf("Sgn error for NaN.\n");
ret = 1;
}
mpfr_clear (x);
if (ret)
exit (ret);
}
int
mpfr_erfc (mpfr_ptr y, mpfr_srcptr x, mpfr_rnd_t rnd)
{
int inex;
mpfr_t tmp;
mpfr_exp_t te, err;
mpfr_prec_t prec;
mpfr_exp_t emin = mpfr_get_emin ();
MPFR_SAVE_EXPO_DECL (expo);
MPFR_ZIV_DECL (loop);
MPFR_LOG_FUNC
(("x[%Pu]=%.*Rg rnd=%d", mpfr_get_prec (x), mpfr_log_prec, x, rnd),
("y[%Pu]=%.*Rg inexact=%d", mpfr_get_prec (y), mpfr_log_prec, y, inex));
if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
{
if (MPFR_IS_NAN (x))
{
MPFR_SET_NAN (y);
MPFR_RET_NAN;
}
/* erfc(+inf) = 0+, erfc(-inf) = 2 erfc (0) = 1 */
else if (MPFR_IS_INF (x))
return mpfr_set_ui (y, MPFR_IS_POS (x) ? 0 : 2, rnd);
else
return mpfr_set_ui (y, 1, rnd);
}
if (MPFR_SIGN (x) > 0)
{
/* by default, emin = 1-2^30, thus the smallest representable
number is 1/2*2^emin = 2^(-2^30):
for x >= 27282, erfc(x) < 2^(-2^30-1), and
for x >= 1787897414, erfc(x) < 2^(-2^62-1).
*/
if ((emin >= -1073741823 && mpfr_cmp_ui (x, 27282) >= 0) ||
mpfr_cmp_ui (x, 1787897414) >= 0)
{
/* May be incorrect if MPFR_EMAX_MAX >= 2^62. */
MPFR_ASSERTN ((MPFR_EMAX_MAX >> 31) >> 31 == 0);
return mpfr_underflow (y, (rnd == MPFR_RNDN) ? MPFR_RNDZ : rnd, 1);
}
}
int
mpfr_ui_sub (mpfr_ptr y, unsigned long int u, mpfr_srcptr x, mpfr_rnd_t rnd_mode)
{
mpfr_t uu;
mp_limb_t up[1];
unsigned long cnt;
MPFR_LOG_FUNC
(("u=%lu x[%Pu]=%.*Rg rnd=%d",
u, mpfr_get_prec(x), mpfr_log_prec, x, rnd_mode),
("y[%Pu]=%.*Rg", mpfr_get_prec(y), mpfr_log_prec, y));
if (MPFR_UNLIKELY (u == 0))
return mpfr_neg (y, x, rnd_mode);
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))
{
/* u - Inf = -Inf and u - -Inf = +Inf */
MPFR_SET_INF(y);
MPFR_SET_OPPOSITE_SIGN(y,x);
MPFR_RET(0); /* +/-infinity is exact */
}
else /* x is zero */
/* u - 0 = u */
return mpfr_set_ui(y, u, rnd_mode);
}
else
{
MPFR_TMP_INIT1 (up, uu, GMP_NUMB_BITS);
MPFR_ASSERTN(u == (mp_limb_t) u);
count_leading_zeros (cnt, (mp_limb_t) u);
*up = (mp_limb_t) u << cnt;
MPFR_SET_EXP (uu, GMP_NUMB_BITS - cnt);
return mpfr_sub (y, uu, x, rnd_mode);
}
}
int
mpfr_set_prec (mpfr_ptr x, mp_prec_t p)
{
mp_size_t xsize;
MPFR_ASSERTN(p >= MPFR_PREC_MIN && p <= MPFR_PREC_MAX);
xsize = (p - 1) / BITS_PER_MP_LIMB + 1; /* new limb size */
if (xsize > MPFR_ABSSIZE(x))
{
MPFR_MANT(x) = (mp_ptr) (*__gmp_reallocate_func)
(MPFR_MANT(x), (size_t) MPFR_ABSSIZE(x) * BYTES_PER_MP_LIMB,
(size_t) xsize * BYTES_PER_MP_LIMB);
MPFR_SIZE(x) = xsize; /* new number of allocated limbs */
}
MPFR_PREC(x) = p;
MPFR_SET_NAN(x); /* initializes to NaN */
return MPFR_MANT(x) == NULL;
}
int
mpfr_ui_sub (mpfr_ptr y, unsigned long int u, mpfr_srcptr x, mp_rnd_t rnd_mode)
{
mpfr_t uu;
mp_limb_t up[1];
unsigned long cnt;
if (MPFR_UNLIKELY (u == 0))
return mpfr_neg (y, x, rnd_mode);
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))
{
/* u - Inf = -Inf and u - -Inf = +Inf */
MPFR_SET_INF(y);
MPFR_SET_OPPOSITE_SIGN(y,x);
MPFR_RET(0); /* +/-infinity is exact */
}
else /* x is zero */
/* u - 0 = u */
return mpfr_set_ui(y, u, rnd_mode);
}
else
{
MPFR_TMP_INIT1 (up, uu, BITS_PER_MP_LIMB);
MPFR_ASSERTN(u == (mp_limb_t) u);
count_leading_zeros (cnt, (mp_limb_t) u);
*up = (mp_limb_t) u << cnt;
MPFR_SET_EXP (uu, BITS_PER_MP_LIMB - cnt);
return mpfr_sub (y, uu, x, rnd_mode);
}
}
MPFR_HOT_FUNCTION_ATTR void
mpfr_set_prec (mpfr_ptr x, mpfr_prec_t p)
{
mp_size_t xsize, xoldsize;
mpfr_limb_ptr tmp;
/* first, check if p is correct */
MPFR_ASSERTN (MPFR_PREC_COND (p));
/* Calculate the new number of limbs */
xsize = MPFR_PREC2LIMBS (p);
/* Realloc only if the new size is greater than the old */
xoldsize = MPFR_GET_ALLOC_SIZE (x);
if (MPFR_UNLIKELY (xsize > xoldsize))
{
tmp = (mpfr_limb_ptr) (*__gmp_reallocate_func)
(MPFR_GET_REAL_PTR(x), MPFR_MALLOC_SIZE(xoldsize), MPFR_MALLOC_SIZE(xsize));
MPFR_SET_MANT_PTR(x, tmp);
MPFR_SET_ALLOC_SIZE(x, xsize);
}
MPFR_PREC (x) = p;
MPFR_SET_NAN (x); /* initializes to NaN */
}
/* 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);
}
}
/* (y, z) <- (sin(x), cos(x)), return value is 0 iff both results are exact
ie, iff x = 0 */
int
mpfr_sin_cos (mpfr_ptr y, mpfr_ptr z, mpfr_srcptr x, mpfr_rnd_t rnd_mode)
{
mpfr_prec_t prec, m;
int neg, reduce;
mpfr_t c, xr;
mpfr_srcptr xx;
mpfr_exp_t err, expx;
int inexy, inexz;
MPFR_ZIV_DECL (loop);
MPFR_SAVE_EXPO_DECL (expo);
MPFR_ASSERTN (y != z);
if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
{
if (MPFR_IS_NAN(x) || MPFR_IS_INF(x))
{
MPFR_SET_NAN (y);
MPFR_SET_NAN (z);
MPFR_RET_NAN;
}
else /* x is zero */
{
MPFR_ASSERTD (MPFR_IS_ZERO (x));
MPFR_SET_ZERO (y);
MPFR_SET_SAME_SIGN (y, x);
/* y = 0, thus exact, but z is inexact in case of underflow
or overflow */
inexy = 0; /* y is exact */
inexz = mpfr_set_ui (z, 1, rnd_mode);
return INEX(inexy,inexz);
}
}
MPFR_LOG_FUNC
(("x[%Pu]=%.*Rg rnd=%d", mpfr_get_prec (x), mpfr_log_prec, x, rnd_mode),
("sin[%Pu]=%.*Rg cos[%Pu]=%.*Rg", mpfr_get_prec(y), mpfr_log_prec, y,
mpfr_get_prec (z), mpfr_log_prec, z));
MPFR_SAVE_EXPO_MARK (expo);
prec = MAX (MPFR_PREC (y), MPFR_PREC (z));
m = prec + MPFR_INT_CEIL_LOG2 (prec) + 13;
expx = MPFR_GET_EXP (x);
/* When x is close to 0, say 2^(-k), then there is a cancellation of about
2k bits in 1-cos(x)^2. FIXME: in that case, it would be more efficient
to compute sin(x) directly. VL: This is partly done by using
MPFR_FAST_COMPUTE_IF_SMALL_INPUT from the mpfr_sin and mpfr_cos
functions. Moreover, any overflow on m is avoided. */
if (expx < 0)
{
/* Warning: in case y = x, and the first call to
MPFR_FAST_COMPUTE_IF_SMALL_INPUT succeeds but the second fails,
we will have clobbered the original value of x.
The workaround is to first compute z = cos(x) in that case, since
y and z are different. */
if (y != x)
/* y and x differ, thus we can safely try to compute y first */
{
MPFR_FAST_COMPUTE_IF_SMALL_INPUT (
y, x, -2 * expx, 2, 0, rnd_mode,
{ inexy = _inexact;
goto small_input; });
/* We use the reflection formula
Gamma(1+t) Gamma(1-t) = - Pi t / sin(Pi (1 + t))
in order to treat the case x <= 1,
i.e. with x = 1-t, then Gamma(x) = -Pi*(1-x)/sin(Pi*(2-x))/GAMMA(2-x)
*/
int
mpfr_gamma (mpfr_ptr gamma, mpfr_srcptr x, mpfr_rnd_t rnd_mode)
{
mpfr_t xp, GammaTrial, tmp, tmp2;
mpz_t fact;
mpfr_prec_t realprec;
int compared, is_integer;
int inex = 0; /* 0 means: result gamma not set yet */
MPFR_GROUP_DECL (group);
MPFR_SAVE_EXPO_DECL (expo);
MPFR_ZIV_DECL (loop);
MPFR_LOG_FUNC
(("x[%Pu]=%.*Rg rnd=%d", mpfr_get_prec (x), mpfr_log_prec, x, rnd_mode),
("gamma[%Pu]=%.*Rg inexact=%d",
mpfr_get_prec (gamma), mpfr_log_prec, gamma, inex));
/* Trivial cases */
if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x)))
{
if (MPFR_IS_NAN (x))
{
MPFR_SET_NAN (gamma);
MPFR_RET_NAN;
}
else if (MPFR_IS_INF (x))
{
if (MPFR_IS_NEG (x))
{
MPFR_SET_NAN (gamma);
MPFR_RET_NAN;
}
else
{
MPFR_SET_INF (gamma);
MPFR_SET_POS (gamma);
MPFR_RET (0); /* exact */
}
}
else /* x is zero */
{
MPFR_ASSERTD(MPFR_IS_ZERO(x));
MPFR_SET_INF(gamma);
MPFR_SET_SAME_SIGN(gamma, x);
MPFR_SET_DIVBY0 ();
MPFR_RET (0); /* exact */
}
}
/* Check for tiny arguments, where gamma(x) ~ 1/x - euler + ....
We know from "Bound on Runs of Zeros and Ones for Algebraic Functions",
Proceedings of Arith15, T. Lang and J.-M. Muller, 2001, that the maximal
number of consecutive zeroes or ones after the round bit is n-1 for an
input of n bits. But we need a more precise lower bound. Assume x has
n bits, and 1/x is near a floating-point number y of n+1 bits. We can
write x = X*2^e, y = Y/2^f with X, Y integers of n and n+1 bits.
Thus X*Y^2^(e-f) is near from 1, i.e., X*Y is near from 2^(f-e).
Two cases can happen:
(i) either X*Y is exactly 2^(f-e), but this can happen only if X and Y
are themselves powers of two, i.e., x is a power of two;
(ii) or X*Y is at distance at least one from 2^(f-e), thus
|xy-1| >= 2^(e-f), or |y-1/x| >= 2^(e-f)/x = 2^(-f)/X >= 2^(-f-n).
Since ufp(y) = 2^(n-f) [ufp = unit in first place], this means
that the distance |y-1/x| >= 2^(-2n) ufp(y).
Now assuming |gamma(x)-1/x| <= 1, which is true for x <= 1,
if 2^(-2n) ufp(y) >= 2, the error is at most 2^(-2n-1) ufp(y),
and round(1/x) with precision >= 2n+2 gives the correct result.
If x < 2^E, then y > 2^(-E), thus ufp(y) > 2^(-E-1).
A sufficient condition is thus EXP(x) + 2 <= -2 MAX(PREC(x),PREC(Y)).
*/
if (MPFR_GET_EXP (x) + 2
<= -2 * (mpfr_exp_t) MAX(MPFR_PREC(x), MPFR_PREC(gamma)))
{
int sign = MPFR_SIGN (x); /* retrieve sign before possible override */
int special;
MPFR_BLOCK_DECL (flags);
MPFR_SAVE_EXPO_MARK (expo);
/* for overflow cases, see below; this needs to be done
before x possibly gets overridden. */
special =
MPFR_GET_EXP (x) == 1 - MPFR_EMAX_MAX &&
MPFR_IS_POS_SIGN (sign) &&
MPFR_IS_LIKE_RNDD (rnd_mode, sign) &&
mpfr_powerof2_raw (x);
MPFR_BLOCK (flags, inex = mpfr_ui_div (gamma, 1, x, rnd_mode));
if (inex == 0) /* x is a power of two */
{
/* return RND(1/x - euler) = RND(+/- 2^k - eps) with eps > 0 */
if (rnd_mode == MPFR_RNDN || MPFR_IS_LIKE_RNDU (rnd_mode, sign))
inex = 1;
else
{
mpfr_nextbelow (gamma);
inex = -1;
}
}
else if (MPFR_UNLIKELY (MPFR_OVERFLOW (flags)))
{
/* Overflow in the division 1/x. This is a real overflow, except
in RNDZ or RNDD when 1/x = 2^emax, i.e. x = 2^(-emax): due to
the "- euler", the rounded value in unbounded exponent range
is 0.111...11 * 2^emax (not an overflow). */
if (!special)
MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, flags);
}
MPFR_SAVE_EXPO_FREE (expo);
/* Note: an overflow is possible with an infinite result;
in this case, the overflow flag will automatically be
restored by mpfr_check_range. */
return mpfr_check_range (gamma, inex, rnd_mode);
}
is_integer = mpfr_integer_p (x);
/* gamma(x) for x a negative integer gives NaN */
if (is_integer && MPFR_IS_NEG(x))
{
MPFR_SET_NAN (gamma);
MPFR_RET_NAN;
}
compared = mpfr_cmp_ui (x, 1);
if (compared == 0)
return mpfr_set_ui (gamma, 1, rnd_mode);
/* if x is an integer that fits into an unsigned long, use mpfr_fac_ui
if argument is not too large.
If precision is p, fac_ui costs O(u*p), whereas gamma costs O(p*M(p)),
so for u <= M(p), fac_ui should be faster.
We approximate here M(p) by p*log(p)^2, which is not a bad guess.
Warning: since the generic code does not handle exact cases,
we want all cases where gamma(x) is exact to be treated here.
*/
if (is_integer && mpfr_fits_ulong_p (x, MPFR_RNDN))
{
unsigned long int u;
mpfr_prec_t p = MPFR_PREC(gamma);
u = mpfr_get_ui (x, MPFR_RNDN);
if (u < 44787929UL && bits_fac (u - 1) <= p + (rnd_mode == MPFR_RNDN))
/* bits_fac: lower bound on the number of bits of m,
where gamma(x) = (u-1)! = m*2^e with m odd. */
return mpfr_fac_ui (gamma, u - 1, rnd_mode);
/* if bits_fac(...) > p (resp. p+1 for rounding to nearest),
then gamma(x) cannot be exact in precision p (resp. p+1).
FIXME: remove the test u < 44787929UL after changing bits_fac
to return a mpz_t or mpfr_t. */
}
MPFR_SAVE_EXPO_MARK (expo);
/* check for overflow: according to (6.1.37) in Abramowitz & Stegun,
gamma(x) >= exp(-x) * x^(x-1/2) * sqrt(2*Pi)
>= 2 * (x/e)^x / x for x >= 1 */
if (compared > 0)
{
mpfr_t yp;
mpfr_exp_t expxp;
MPFR_BLOCK_DECL (flags);
/* quick test for the default exponent range */
if (mpfr_get_emax () >= 1073741823UL && MPFR_GET_EXP(x) <= 25)
{
MPFR_SAVE_EXPO_FREE (expo);
return mpfr_gamma_aux (gamma, x, rnd_mode);
}
/* 1/e rounded down to 53 bits */
#define EXPM1_STR "0.010111100010110101011000110110001011001110111100111"
mpfr_init2 (xp, 53);
mpfr_init2 (yp, 53);
mpfr_set_str_binary (xp, EXPM1_STR);
mpfr_mul (xp, x, xp, MPFR_RNDZ);
mpfr_sub_ui (yp, x, 2, MPFR_RNDZ);
mpfr_pow (xp, xp, yp, MPFR_RNDZ); /* (x/e)^(x-2) */
mpfr_set_str_binary (yp, EXPM1_STR);
mpfr_mul (xp, xp, yp, MPFR_RNDZ); /* x^(x-2) / e^(x-1) */
mpfr_mul (xp, xp, yp, MPFR_RNDZ); /* x^(x-2) / e^x */
mpfr_mul (xp, xp, x, MPFR_RNDZ); /* lower bound on x^(x-1) / e^x */
MPFR_BLOCK (flags, mpfr_mul_2ui (xp, xp, 1, MPFR_RNDZ));
expxp = MPFR_GET_EXP (xp);
mpfr_clear (xp);
mpfr_clear (yp);
MPFR_SAVE_EXPO_FREE (expo);
return MPFR_OVERFLOW (flags) || expxp > __gmpfr_emax ?
mpfr_overflow (gamma, rnd_mode, 1) :
mpfr_gamma_aux (gamma, x, rnd_mode);
}
/* now compared < 0 */
/* check for underflow: for x < 1,
gamma(x) = Pi*(x-1)/sin(Pi*(2-x))/gamma(2-x).
Since gamma(2-x) >= 2 * ((2-x)/e)^(2-x) / (2-x), we have
|gamma(x)| <= Pi*(1-x)*(2-x)/2/((2-x)/e)^(2-x) / |sin(Pi*(2-x))|
<= 12 * ((2-x)/e)^x / |sin(Pi*(2-x))|.
To avoid an underflow in ((2-x)/e)^x, we compute the logarithm.
*/
if (MPFR_IS_NEG(x))
{
int underflow = 0, sgn, ck;
mpfr_prec_t w;
mpfr_init2 (xp, 53);
mpfr_init2 (tmp, 53);
mpfr_init2 (tmp2, 53);
/* we want an upper bound for x * [log(2-x)-1].
since x < 0, we need a lower bound on log(2-x) */
mpfr_ui_sub (xp, 2, x, MPFR_RNDD);
mpfr_log (xp, xp, MPFR_RNDD);
mpfr_sub_ui (xp, xp, 1, MPFR_RNDD);
mpfr_mul (xp, xp, x, MPFR_RNDU);
/* we need an upper bound on 1/|sin(Pi*(2-x))|,
thus a lower bound on |sin(Pi*(2-x))|.
If 2-x is exact, then the error of Pi*(2-x) is (1+u)^2 with u = 2^(-p)
thus the error on sin(Pi*(2-x)) is less than 1/2ulp + 3Pi(2-x)u,
assuming u <= 1, thus <= u + 3Pi(2-x)u */
w = mpfr_gamma_2_minus_x_exact (x); /* 2-x is exact for prec >= w */
w += 17; /* to get tmp2 small enough */
mpfr_set_prec (tmp, w);
mpfr_set_prec (tmp2, w);
MPFR_DBGRES (ck = mpfr_ui_sub (tmp, 2, x, MPFR_RNDN));
MPFR_ASSERTD (ck == 0); /* tmp = 2-x exactly */
mpfr_const_pi (tmp2, MPFR_RNDN);
mpfr_mul (tmp2, tmp2, tmp, MPFR_RNDN); /* Pi*(2-x) */
mpfr_sin (tmp, tmp2, MPFR_RNDN); /* sin(Pi*(2-x)) */
sgn = mpfr_sgn (tmp);
mpfr_abs (tmp, tmp, MPFR_RNDN);
mpfr_mul_ui (tmp2, tmp2, 3, MPFR_RNDU); /* 3Pi(2-x) */
mpfr_add_ui (tmp2, tmp2, 1, MPFR_RNDU); /* 3Pi(2-x)+1 */
mpfr_div_2ui (tmp2, tmp2, mpfr_get_prec (tmp), MPFR_RNDU);
/* if tmp2<|tmp|, we get a lower bound */
if (mpfr_cmp (tmp2, tmp) < 0)
{
mpfr_sub (tmp, tmp, tmp2, MPFR_RNDZ); /* low bnd on |sin(Pi*(2-x))| */
mpfr_ui_div (tmp, 12, tmp, MPFR_RNDU); /* upper bound */
mpfr_log2 (tmp, tmp, MPFR_RNDU);
mpfr_add (xp, tmp, xp, MPFR_RNDU);
/* The assert below checks that expo.saved_emin - 2 always
fits in a long. FIXME if we want to allow mpfr_exp_t to
be a long long, for instance. */
MPFR_ASSERTN (MPFR_EMIN_MIN - 2 >= LONG_MIN);
underflow = mpfr_cmp_si (xp, expo.saved_emin - 2) <= 0;
}
mpfr_clear (xp);
mpfr_clear (tmp);
mpfr_clear (tmp2);
if (underflow) /* the sign is the opposite of that of sin(Pi*(2-x)) */
{
MPFR_SAVE_EXPO_FREE (expo);
return mpfr_underflow (gamma, (rnd_mode == MPFR_RNDN) ? MPFR_RNDZ : rnd_mode, -sgn);
}
}
realprec = MPFR_PREC (gamma);
/* we want both 1-x and 2-x to be exact */
{
mpfr_prec_t w;
w = mpfr_gamma_1_minus_x_exact (x);
if (realprec < w)
realprec = w;
w = mpfr_gamma_2_minus_x_exact (x);
if (realprec < w)
realprec = w;
}
realprec = realprec + MPFR_INT_CEIL_LOG2 (realprec) + 20;
MPFR_ASSERTD(realprec >= 5);
MPFR_GROUP_INIT_4 (group, realprec + MPFR_INT_CEIL_LOG2 (realprec) + 20,
xp, tmp, tmp2, GammaTrial);
mpz_init (fact);
MPFR_ZIV_INIT (loop, realprec);
for (;;)
{
mpfr_exp_t err_g;
int ck;
MPFR_GROUP_REPREC_4 (group, realprec, xp, tmp, tmp2, GammaTrial);
/* reflection formula: gamma(x) = Pi*(x-1)/sin(Pi*(2-x))/gamma(2-x) */
ck = mpfr_ui_sub (xp, 2, x, MPFR_RNDN); /* 2-x, exact */
MPFR_ASSERTD(ck == 0); (void) ck; /* use ck to avoid a warning */
mpfr_gamma (tmp, xp, MPFR_RNDN); /* gamma(2-x), error (1+u) */
mpfr_const_pi (tmp2, MPFR_RNDN); /* Pi, error (1+u) */
mpfr_mul (GammaTrial, tmp2, xp, MPFR_RNDN); /* Pi*(2-x), error (1+u)^2 */
err_g = MPFR_GET_EXP(GammaTrial);
mpfr_sin (GammaTrial, GammaTrial, MPFR_RNDN); /* sin(Pi*(2-x)) */
/* If tmp is +Inf, we compute exp(lngamma(x)). */
if (mpfr_inf_p (tmp))
{
inex = mpfr_explgamma (gamma, x, &expo, tmp, tmp2, rnd_mode);
if (inex)
goto end;
else
goto ziv_next;
}
err_g = err_g + 1 - MPFR_GET_EXP(GammaTrial);
/* let g0 the true value of Pi*(2-x), g the computed value.
We have g = g0 + h with |h| <= |(1+u^2)-1|*g.
Thus sin(g) = sin(g0) + h' with |h'| <= |(1+u^2)-1|*g.
The relative error is thus bounded by |(1+u^2)-1|*g/sin(g)
<= |(1+u^2)-1|*2^err_g. <= 2.25*u*2^err_g for |u|<=1/4.
With the rounding error, this gives (0.5 + 2.25*2^err_g)*u. */
ck = mpfr_sub_ui (xp, x, 1, MPFR_RNDN); /* x-1, exact */
MPFR_ASSERTD(ck == 0); (void) ck; /* use ck to avoid a warning */
mpfr_mul (xp, tmp2, xp, MPFR_RNDN); /* Pi*(x-1), error (1+u)^2 */
mpfr_mul (GammaTrial, GammaTrial, tmp, MPFR_RNDN);
/* [1 + (0.5 + 2.25*2^err_g)*u]*(1+u)^2 = 1 + (2.5 + 2.25*2^err_g)*u
+ (0.5 + 2.25*2^err_g)*u*(2u+u^2) + u^2.
For err_g <= realprec-2, we have (0.5 + 2.25*2^err_g)*u <=
0.5*u + 2.25/4 <= 0.6875 and u^2 <= u/4, thus
(0.5 + 2.25*2^err_g)*u*(2u+u^2) + u^2 <= 0.6875*(2u+u/4) + u/4
<= 1.8*u, thus the rel. error is bounded by (4.5 + 2.25*2^err_g)*u. */
mpfr_div (GammaTrial, xp, GammaTrial, MPFR_RNDN);
/* the error is of the form (1+u)^3/[1 + (4.5 + 2.25*2^err_g)*u].
For realprec >= 5 and err_g <= realprec-2, [(4.5 + 2.25*2^err_g)*u]^2
<= 0.71, and for |y|<=0.71, 1/(1-y) can be written 1+a*y with a<=4.
(1+u)^3 * (1+4*(4.5 + 2.25*2^err_g)*u)
= 1 + (21 + 9*2^err_g)*u + (57+27*2^err_g)*u^2 + (55+27*2^err_g)*u^3
+ (18+9*2^err_g)*u^4
<= 1 + (21 + 9*2^err_g)*u + (57+27*2^err_g)*u^2 + (56+28*2^err_g)*u^3
<= 1 + (21 + 9*2^err_g)*u + (59+28*2^err_g)*u^2
<= 1 + (23 + 10*2^err_g)*u.
The final error is thus bounded by (23 + 10*2^err_g) ulps,
which is <= 2^6 for err_g<=2, and <= 2^(err_g+4) for err_g >= 2. */
err_g = (err_g <= 2) ? 6 : err_g + 4;
if (MPFR_LIKELY (MPFR_CAN_ROUND (GammaTrial, realprec - err_g,
MPFR_PREC(gamma), rnd_mode)))
break;
ziv_next:
MPFR_ZIV_NEXT (loop, realprec);
}
end:
MPFR_ZIV_FREE (loop);
if (inex == 0)
inex = mpfr_set (gamma, GammaTrial, rnd_mode);
MPFR_GROUP_CLEAR (group);
mpz_clear (fact);
MPFR_SAVE_EXPO_FREE (expo);
return mpfr_check_range (gamma, inex, rnd_mode);
}
int
mpfr_exp (mpfr_ptr y, mpfr_srcptr x, mpfr_rnd_t rnd_mode)
{
mpfr_exp_t expx;
mpfr_prec_t precy;
int inexact;
MPFR_SAVE_EXPO_DECL (expo);
MPFR_LOG_FUNC (("x[%#R]=%R rnd=%d", x, x, rnd_mode),
("y[%#R]=%R inexact=%d", y, 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
{
MPFR_ASSERTD(MPFR_IS_ZERO(x));
return mpfr_set_ui (y, 1, rnd_mode);
}
}
/* First, let's detect most overflow and underflow cases. */
{
mpfr_t e, bound;
/* We must extended the exponent range and save the flags now. */
MPFR_SAVE_EXPO_MARK (expo);
mpfr_init2 (e, sizeof (mpfr_exp_t) * CHAR_BIT);
mpfr_init2 (bound, 32);
inexact = mpfr_set_exp_t (e, expo.saved_emax, MPFR_RNDN);
MPFR_ASSERTD (inexact == 0);
mpfr_const_log2 (bound, expo.saved_emax < 0 ? MPFR_RNDD : MPFR_RNDU);
mpfr_mul (bound, bound, e, MPFR_RNDU);
if (MPFR_UNLIKELY (mpfr_cmp (x, bound) >= 0))
{
/* x > log(2^emax), thus exp(x) > 2^emax */
mpfr_clears (e, bound, (mpfr_ptr) 0);
MPFR_SAVE_EXPO_FREE (expo);
return mpfr_overflow (y, rnd_mode, 1);
}
inexact = mpfr_set_exp_t (e, expo.saved_emin, MPFR_RNDN);
MPFR_ASSERTD (inexact == 0);
inexact = mpfr_sub_ui (e, e, 2, MPFR_RNDN);
MPFR_ASSERTD (inexact == 0);
mpfr_const_log2 (bound, expo.saved_emin < 0 ? MPFR_RNDU : MPFR_RNDD);
mpfr_mul (bound, bound, e, MPFR_RNDD);
if (MPFR_UNLIKELY (mpfr_cmp (x, bound) <= 0))
{
/* x < log(2^(emin - 2)), thus exp(x) < 2^(emin - 2) */
mpfr_clears (e, bound, (mpfr_ptr) 0);
MPFR_SAVE_EXPO_FREE (expo);
return mpfr_underflow (y, rnd_mode == MPFR_RNDN ? MPFR_RNDZ : rnd_mode,
1);
}
/* Other overflow/underflow cases must be detected
by the generic routines. */
mpfr_clears (e, bound, (mpfr_ptr) 0);
MPFR_SAVE_EXPO_FREE (expo);
}
expx = MPFR_GET_EXP (x);
precy = MPFR_PREC (y);
/* if x < 2^(-precy), then exp(x) i.e. gives 1 +/- 1 ulp(1) */
if (MPFR_UNLIKELY (expx < 0 && (mpfr_uexp_t) (-expx) > precy))
{
mpfr_exp_t emin = __gmpfr_emin;
mpfr_exp_t emax = __gmpfr_emax;
int signx = MPFR_SIGN (x);
MPFR_SET_POS (y);
if (MPFR_IS_NEG_SIGN (signx) && (rnd_mode == MPFR_RNDD ||
rnd_mode == MPFR_RNDZ))
{
__gmpfr_emin = 0;
__gmpfr_emax = 0;
mpfr_setmax (y, 0); /* y = 1 - epsilon */
inexact = -1;
}
else
{
__gmpfr_emin = 1;
__gmpfr_emax = 1;
mpfr_setmin (y, 1); /* y = 1 */
if (MPFR_IS_POS_SIGN (signx) && (rnd_mode == MPFR_RNDU ||
rnd_mode == MPFR_RNDA))
{
mp_size_t yn;
int sh;
yn = 1 + (MPFR_PREC(y) - 1) / GMP_NUMB_BITS;
sh = (mpfr_prec_t) yn * GMP_NUMB_BITS - MPFR_PREC(y);
MPFR_MANT(y)[0] += MPFR_LIMB_ONE << sh;
inexact = 1;
}
else
inexact = -MPFR_FROM_SIGN_TO_INT(signx);
}
__gmpfr_emin = emin;
__gmpfr_emax = emax;
}
else /* General case */
{
if (MPFR_UNLIKELY (precy >= MPFR_EXP_THRESHOLD))
/* mpfr_exp_3 saves the exponent range and flags itself, otherwise
the flag changes in mpfr_exp_3 are lost */
inexact = mpfr_exp_3 (y, x, rnd_mode); /* O(M(n) log(n)^2) */
else
{
MPFR_SAVE_EXPO_MARK (expo);
inexact = mpfr_exp_2 (y, x, rnd_mode); /* O(n^(1/3) M(n)) */
MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, __gmpfr_flags);
MPFR_SAVE_EXPO_FREE (expo);
}
}
return mpfr_check_range (y, inexact, rnd_mode);
}
int
mpfr_atanh (mpfr_ptr y, mpfr_srcptr xt , mpfr_rnd_t rnd_mode)
{
int inexact;
mpfr_t x, t, te;
mpfr_prec_t Nx, Ny, Nt;
mpfr_exp_t err;
MPFR_ZIV_DECL (loop);
MPFR_SAVE_EXPO_DECL (expo);
MPFR_LOG_FUNC
(("x[%Pu]=%.*Rg rnd=%d", mpfr_get_prec (xt), mpfr_log_prec, xt, rnd_mode),
("y[%Pu]=%.*Rg inexact=%d",
mpfr_get_prec (y), mpfr_log_prec, y, inexact));
/* Special cases */
if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (xt)))
{
/* atanh(NaN) = NaN, and atanh(+/-Inf) = NaN since tanh gives a result
between -1 and 1 */
if (MPFR_IS_NAN (xt) || MPFR_IS_INF (xt))
{
MPFR_SET_NAN (y);
MPFR_RET_NAN;
}
else /* necessarily xt is 0 */
{
MPFR_ASSERTD (MPFR_IS_ZERO (xt));
MPFR_SET_ZERO (y); /* atanh(0) = 0 */
MPFR_SET_SAME_SIGN (y,xt);
MPFR_RET (0);
}
}
/* atanh (x) = NaN as soon as |x| > 1, and arctanh(+/-1) = +/-Inf */
if (MPFR_UNLIKELY (MPFR_GET_EXP (xt) > 0))
{
if (MPFR_GET_EXP (xt) == 1 && mpfr_powerof2_raw (xt))
{
MPFR_SET_INF (y);
MPFR_SET_SAME_SIGN (y, xt);
mpfr_set_divby0 ();
MPFR_RET (0);
}
MPFR_SET_NAN (y);
MPFR_RET_NAN;
}
/* atanh(x) = x + x^3/3 + ... so the error is < 2^(3*EXP(x)-1) */
MPFR_FAST_COMPUTE_IF_SMALL_INPUT (y, xt, -2 * MPFR_GET_EXP (xt), 1, 1,
rnd_mode, {});
MPFR_SAVE_EXPO_MARK (expo);
/* Compute initial precision */
Nx = MPFR_PREC (xt);
MPFR_TMP_INIT_ABS (x, xt);
Ny = MPFR_PREC (y);
Nt = MAX (Nx, Ny);
/* the optimal number of bits : see algorithms.ps */
Nt = Nt + MPFR_INT_CEIL_LOG2 (Nt) + 4;
/* initialise of intermediary variable */
mpfr_init2 (t, Nt);
mpfr_init2 (te, Nt);
/* First computation of cosh */
MPFR_ZIV_INIT (loop, Nt);
for (;;)
{
/* compute atanh */
mpfr_ui_sub (te, 1, x, MPFR_RNDU); /* (1-xt)*/
mpfr_add_ui (t, x, 1, MPFR_RNDD); /* (xt+1)*/
mpfr_div (t, t, te, MPFR_RNDN); /* (1+xt)/(1-xt)*/
mpfr_log (t, t, MPFR_RNDN); /* ln((1+xt)/(1-xt))*/
mpfr_div_2ui (t, t, 1, MPFR_RNDN); /* (1/2)*ln((1+xt)/(1-xt))*/
/* error estimate: see algorithms.tex */
/* FIXME: this does not correspond to the value in algorithms.tex!!! */
/* err=Nt-__gmpfr_ceil_log2(1+5*pow(2,1-MPFR_EXP(t)));*/
err = Nt - (MAX (4 - MPFR_GET_EXP (t), 0) + 1);
if (MPFR_LIKELY (MPFR_IS_ZERO (t)
|| MPFR_CAN_ROUND (t, err, Ny, rnd_mode)))
break;
/* reactualisation of the precision */
MPFR_ZIV_NEXT (loop, Nt);
mpfr_set_prec (t, Nt);
mpfr_set_prec (te, Nt);
}
MPFR_ZIV_FREE (loop);
inexact = mpfr_set4 (y, t, rnd_mode, MPFR_SIGN (xt));
mpfr_clear(t);
mpfr_clear(te);
MPFR_SAVE_EXPO_FREE (expo);
return mpfr_check_range (y, inexact, rnd_mode);
}
