static PyObject *
GMPy_Complex_Norm(PyObject *x, CTXT_Object *context)
{
MPFR_Object *result;
MPC_Object *tempx;
CHECK_CONTEXT(context);
result = GMPy_MPFR_New(0, context);
tempx = GMPy_MPC_From_Complex(x, 1, 1, context);
if (!result || !tempx) {
return NULL;
}
mpfr_clear_flags();
result->rc = mpc_norm(result->f, tempx->c, GET_MPFR_ROUND(context));
Py_DECREF((PyObject*)tempx);
GMPY_MPFR_CLEANUP(result, context, "norm()");
return (PyObject*)result;
}
/* return mpfr_cmp (mpc_abs (a), mpc_abs (b)) */
int
mpc_cmp_abs (mpc_srcptr a, mpc_srcptr b)
{
mpc_t z1, z2;
mpfr_t n1, n2;
mpfr_prec_t prec;
int inex1, inex2, ret;
/* Handle numbers containing one NaN as mpfr_cmp. */
if ( mpfr_nan_p (mpc_realref (a)) || mpfr_nan_p (mpc_imagref (a))
|| mpfr_nan_p (mpc_realref (b)) || mpfr_nan_p (mpc_imagref (b)))
{
mpfr_t nan;
mpfr_init (nan);
mpfr_set_nan (nan);
ret = mpfr_cmp (nan, nan);
mpfr_clear (nan);
return ret;
}
/* Handle infinities. */
if (mpc_inf_p (a))
if (mpc_inf_p (b))
return 0;
else
return 1;
else if (mpc_inf_p (b))
return -1;
/* Replace all parts of a and b by their absolute values, then order
them by size. */
z1 [0] = a [0];
z2 [0] = b [0];
if (mpfr_signbit (mpc_realref (a)))
MPFR_CHANGE_SIGN (mpc_realref (z1));
if (mpfr_signbit (mpc_imagref (a)))
MPFR_CHANGE_SIGN (mpc_imagref (z1));
if (mpfr_signbit (mpc_realref (b)))
MPFR_CHANGE_SIGN (mpc_realref (z2));
if (mpfr_signbit (mpc_imagref (b)))
MPFR_CHANGE_SIGN (mpc_imagref (z2));
if (mpfr_cmp (mpc_realref (z1), mpc_imagref (z1)) > 0)
mpfr_swap (mpc_realref (z1), mpc_imagref (z1));
if (mpfr_cmp (mpc_realref (z2), mpc_imagref (z2)) > 0)
mpfr_swap (mpc_realref (z2), mpc_imagref (z2));
/* Handle cases in which only one part differs. */
if (mpfr_cmp (mpc_realref (z1), mpc_realref (z2)) == 0)
return mpfr_cmp (mpc_imagref (z1), mpc_imagref (z2));
if (mpfr_cmp (mpc_imagref (z1), mpc_imagref (z2)) == 0)
return mpfr_cmp (mpc_realref (z1), mpc_realref (z2));
/* Implement the algorithm in algorithms.tex. */
mpfr_init (n1);
mpfr_init (n2);
prec = MPC_MAX (50, MPC_MAX (MPC_MAX_PREC (z1), MPC_MAX_PREC (z2)) / 100);
do {
mpfr_set_prec (n1, prec);
mpfr_set_prec (n2, prec);
inex1 = mpc_norm (n1, z1, MPFR_RNDD);
inex2 = mpc_norm (n2, z2, MPFR_RNDD);
ret = mpfr_cmp (n1, n2);
if (ret != 0)
goto end;
else
if (inex1 == 0) /* n1 = norm(z1) */
if (inex2) /* n2 < norm(z2) */
{
ret = -1;
goto end;
}
else /* n2 = norm(z2) */
{
ret = 0;
goto end;
}
else /* n1 < norm(z1) */
if (inex2 == 0)
{
ret = 1;
goto end;
}
prec *= 2;
} while (1);
end:
mpfr_clear (n1);
mpfr_clear (n2);
return ret;
}
/* Put in z the value of x^y, rounded according to 'rnd'.
Return the inexact flag in [0, 10]. */
int
mpc_pow (mpc_ptr z, mpc_srcptr x, mpc_srcptr y, mpc_rnd_t rnd)
{
int ret = -2, loop, x_real, x_imag, y_real, z_real = 0, z_imag = 0;
mpc_t t, u;
mpfr_prec_t p, pr, pi, maxprec;
int saved_underflow, saved_overflow;
/* save the underflow or overflow flags from MPFR */
saved_underflow = mpfr_underflow_p ();
saved_overflow = mpfr_overflow_p ();
x_real = mpfr_zero_p (mpc_imagref(x));
y_real = mpfr_zero_p (mpc_imagref(y));
if (y_real && mpfr_zero_p (mpc_realref(y))) /* case y zero */
{
if (x_real && mpfr_zero_p (mpc_realref(x)))
{
/* we define 0^0 to be (1, +0) since the real part is
coherent with MPFR where 0^0 gives 1, and the sign of the
imaginary part cannot be determined */
mpc_set_ui_ui (z, 1, 0, MPC_RNDNN);
return 0;
}
else /* x^0 = 1 +/- i*0 even for x=NaN see algorithms.tex for the
sign of zero */
{
mpfr_t n;
int inex, cx1;
int sign_zi;
/* cx1 < 0 if |x| < 1
cx1 = 0 if |x| = 1
cx1 > 0 if |x| > 1
*/
mpfr_init (n);
inex = mpc_norm (n, x, MPFR_RNDN);
cx1 = mpfr_cmp_ui (n, 1);
if (cx1 == 0 && inex != 0)
cx1 = -inex;
sign_zi = (cx1 < 0 && mpfr_signbit (mpc_imagref (y)) == 0)
|| (cx1 == 0
&& mpfr_signbit (mpc_imagref (x)) != mpfr_signbit (mpc_realref (y)))
|| (cx1 > 0 && mpfr_signbit (mpc_imagref (y)));
/* warning: mpc_set_ui_ui does not set Im(z) to -0 if Im(rnd)=RNDD */
ret = mpc_set_ui_ui (z, 1, 0, rnd);
if (MPC_RND_IM (rnd) == MPFR_RNDD || sign_zi)
mpc_conj (z, z, MPC_RNDNN);
mpfr_clear (n);
return ret;
}
}
if (!mpc_fin_p (x) || !mpc_fin_p (y))
{
/* special values: exp(y*log(x)) */
mpc_init2 (u, 2);
mpc_log (u, x, MPC_RNDNN);
mpc_mul (u, u, y, MPC_RNDNN);
ret = mpc_exp (z, u, rnd);
mpc_clear (u);
goto end;
}
if (x_real) /* case x real */
{
if (mpfr_zero_p (mpc_realref(x))) /* x is zero */
{
/* special values: exp(y*log(x)) */
mpc_init2 (u, 2);
mpc_log (u, x, MPC_RNDNN);
mpc_mul (u, u, y, MPC_RNDNN);
ret = mpc_exp (z, u, rnd);
mpc_clear (u);
goto end;
}
/* Special case 1^y = 1 */
if (mpfr_cmp_ui (mpc_realref(x), 1) == 0)
{
int s1, s2;
s1 = mpfr_signbit (mpc_realref (y));
s2 = mpfr_signbit (mpc_imagref (x));
ret = mpc_set_ui (z, +1, rnd);
/* the sign of the zero imaginary part is known in some cases (see
algorithm.tex). In such cases we have
(x +s*0i)^(y+/-0i) = x^y + s*sign(y)*0i
where s = +/-1. We extend here this rule to fix the sign of the
zero part.
Note that the sign must also be set explicitly when rnd=RNDD
because mpfr_set_ui(z_i, 0, rnd) always sets z_i to +0.
*/
if (MPC_RND_IM (rnd) == MPFR_RNDD || s1 != s2)
mpc_conj (z, z, MPC_RNDNN);
goto end;
}
/* x^y is real when:
(a) x is real and y is integer
(b) x is real non-negative and y is real */
if (y_real && (mpfr_integer_p (mpc_realref(y)) ||
mpfr_cmp_ui (mpc_realref(x), 0) >= 0))
{
int s1, s2;
s1 = mpfr_signbit (mpc_realref (y));
s2 = mpfr_signbit (mpc_imagref (x));
ret = mpfr_pow (mpc_realref(z), mpc_realref(x), mpc_realref(y), MPC_RND_RE(rnd));
ret = MPC_INEX(ret, mpfr_set_ui (mpc_imagref(z), 0, MPC_RND_IM(rnd)));
/* the sign of the zero imaginary part is known in some cases
(see algorithm.tex). In such cases we have (x +s*0i)^(y+/-0i)
= x^y + s*sign(y)*0i where s = +/-1.
We extend here this rule to fix the sign of the zero part.
Note that the sign must also be set explicitly when rnd=RNDD
because mpfr_set_ui(z_i, 0, rnd) always sets z_i to +0.
*/
if (MPC_RND_IM(rnd) == MPFR_RNDD || s1 != s2)
mpfr_neg (mpc_imagref(z), mpc_imagref(z), MPC_RND_IM(rnd));
goto end;
}
/* (-1)^(n+I*t) is real for n integer and t real */
if (mpfr_cmp_si (mpc_realref(x), -1) == 0 && mpfr_integer_p (mpc_realref(y)))
z_real = 1;
/* for x real, x^y is imaginary when:
(a) x is negative and y is half-an-integer
(b) x = -1 and Re(y) is half-an-integer
*/
if ((mpfr_cmp_ui (mpc_realref(x), 0) < 0) && is_odd (mpc_realref(y), 1)
&& (y_real || mpfr_cmp_si (mpc_realref(x), -1) == 0))
z_imag = 1;
}
else /* x non real */
/* I^(t*I) and (-I)^(t*I) are real for t real,
I^(n+t*I) and (-I)^(n+t*I) are real for n even and t real, and
I^(n+t*I) and (-I)^(n+t*I) are imaginary for n odd and t real
(s*I)^n is real for n even and imaginary for n odd */
if ((mpc_cmp_si_si (x, 0, 1) == 0 || mpc_cmp_si_si (x, 0, -1) == 0 ||
(mpfr_cmp_ui (mpc_realref(x), 0) == 0 && y_real)) &&
mpfr_integer_p (mpc_realref(y)))
{ /* x is I or -I, and Re(y) is an integer */
if (is_odd (mpc_realref(y), 0))
z_imag = 1; /* Re(y) odd: z is imaginary */
else
z_real = 1; /* Re(y) even: z is real */
}
else /* (t+/-t*I)^(2n) is imaginary for n odd and real for n even */
if (mpfr_cmpabs (mpc_realref(x), mpc_imagref(x)) == 0 && y_real &&
mpfr_integer_p (mpc_realref(y)) && is_odd (mpc_realref(y), 0) == 0)
{
if (is_odd (mpc_realref(y), -1)) /* y/2 is odd */
z_imag = 1;
else
z_real = 1;
}
pr = mpfr_get_prec (mpc_realref(z));
pi = mpfr_get_prec (mpc_imagref(z));
p = (pr > pi) ? pr : pi;
p += 12; /* experimentally, seems to give less than 10% of failures in
Ziv's strategy; probably wrong now since q is not computed */
if (p < 64)
p = 64;
mpc_init2 (u, p);
mpc_init2 (t, p);
pr += MPC_RND_RE(rnd) == MPFR_RNDN;
pi += MPC_RND_IM(rnd) == MPFR_RNDN;
maxprec = MPC_MAX_PREC (z);
x_imag = mpfr_zero_p (mpc_realref(x));
for (loop = 0;; loop++)
{
int ret_exp;
mpfr_exp_t dr, di;
mpfr_prec_t q;
mpc_log (t, x, MPC_RNDNN);
mpc_mul (t, t, y, MPC_RNDNN);
/* Compute q such that |Re (y log x)|, |Im (y log x)| < 2^q.
We recompute it at each loop since we might get different
bounds if the precision is not enough. */
q = mpfr_get_exp (mpc_realref(t)) > 0 ? mpfr_get_exp (mpc_realref(t)) : 0;
if (mpfr_get_exp (mpc_imagref(t)) > (mpfr_exp_t) q)
q = mpfr_get_exp (mpc_imagref(t));
mpfr_clear_overflow ();
mpfr_clear_underflow ();
ret_exp = mpc_exp (u, t, MPC_RNDNN);
if (mpfr_underflow_p () || mpfr_overflow_p ()) {
/* under- and overflow flags are set by mpc_exp */
mpc_set (z, u, MPC_RNDNN);
ret = ret_exp;
goto exact;
}
/* Since the error bound is global, we have to take into account the
exponent difference between the real and imaginary parts. We assume
either the real or the imaginary part of u is not zero.
*/
dr = mpfr_zero_p (mpc_realref(u)) ? mpfr_get_exp (mpc_imagref(u))
: mpfr_get_exp (mpc_realref(u));
di = mpfr_zero_p (mpc_imagref(u)) ? dr : mpfr_get_exp (mpc_imagref(u));
if (dr > di)
{
di = dr - di;
dr = 0;
}
else
{
dr = di - dr;
di = 0;
}
/* the term -3 takes into account the factor 4 in the complex error
(see algorithms.tex) plus one due to the exponent difference: if
z = a + I*b, where the relative error on z is at most 2^(-p), and
EXP(a) = EXP(b) + k, the relative error on b is at most 2^(k-p) */
if ((z_imag || (p > q + 3 + dr && mpfr_can_round (mpc_realref(u), p - q - 3 - dr, MPFR_RNDN, MPFR_RNDZ, pr))) &&
(z_real || (p > q + 3 + di && mpfr_can_round (mpc_imagref(u), p - q - 3 - di, MPFR_RNDN, MPFR_RNDZ, pi))))
break;
/* if Re(u) is not known to be zero, assume it is a normal number, i.e.,
neither zero, Inf or NaN, otherwise we might enter an infinite loop */
MPC_ASSERT (z_imag || mpfr_number_p (mpc_realref(u)));
/* idem for Im(u) */
MPC_ASSERT (z_real || mpfr_number_p (mpc_imagref(u)));
if (ret == -2) /* we did not yet call mpc_pow_exact, or it aborted
because intermediate computations had > maxprec bits */
{
/* check exact cases (see algorithms.tex) */
if (y_real)
{
maxprec *= 2;
ret = mpc_pow_exact (z, x, mpc_realref(y), rnd, maxprec);
if (ret != -1 && ret != -2)
goto exact;
}
p += dr + di + 64;
}
else
p += p / 2;
mpc_set_prec (t, p);
mpc_set_prec (u, p);
}
if (z_real)
{
/* When the result is real (see algorithm.tex for details),
Im(x^y) =
+ sign(imag(y))*0i, if |x| > 1
+ sign(imag(x))*sign(real(y))*0i, if |x| = 1
- sign(imag(y))*0i, if |x| < 1
*/
mpfr_t n;
int inex, cx1;
int sign_zi, sign_rex, sign_imx;
/* cx1 < 0 if |x| < 1
cx1 = 0 if |x| = 1
cx1 > 0 if |x| > 1
*/
sign_rex = mpfr_signbit (mpc_realref (x));
sign_imx = mpfr_signbit (mpc_imagref (x));
mpfr_init (n);
inex = mpc_norm (n, x, MPFR_RNDN);
cx1 = mpfr_cmp_ui (n, 1);
if (cx1 == 0 && inex != 0)
cx1 = -inex;
sign_zi = (cx1 < 0 && mpfr_signbit (mpc_imagref (y)) == 0)
|| (cx1 == 0 && sign_imx != mpfr_signbit (mpc_realref (y)))
|| (cx1 > 0 && mpfr_signbit (mpc_imagref (y)));
/* copy RE(y) to n since if z==y we will destroy Re(y) below */
mpfr_set_prec (n, mpfr_get_prec (mpc_realref (y)));
mpfr_set (n, mpc_realref (y), MPFR_RNDN);
ret = mpfr_set (mpc_realref(z), mpc_realref(u), MPC_RND_RE(rnd));
if (y_real && (x_real || x_imag))
{
/* FIXME: with y_real we assume Im(y) is really 0, which is the case
for example when y comes from pow_fr, but in case Im(y) is +0 or
-0, we might get different results */
mpfr_set_ui (mpc_imagref (z), 0, MPC_RND_IM (rnd));
fix_sign (z, sign_rex, sign_imx, n);
ret = MPC_INEX(ret, 0); /* imaginary part is exact */
}
else
{
ret = MPC_INEX (ret, mpfr_set_ui (mpc_imagref (z), 0, MPC_RND_IM (rnd)));
/* warning: mpfr_set_ui does not set Im(z) to -0 if Im(rnd) = RNDD */
if (MPC_RND_IM (rnd) == MPFR_RNDD || sign_zi)
mpc_conj (z, z, MPC_RNDNN);
}
mpfr_clear (n);
}
else if (z_imag)
{
ret = mpfr_set (mpc_imagref(z), mpc_imagref(u), MPC_RND_IM(rnd));
/* if z is imaginary and y real, then x cannot be real */
if (y_real && x_imag)
{
int sign_rex = mpfr_signbit (mpc_realref (x));
/* If z overlaps with y we set Re(z) before checking Re(y) below,
but in that case y=0, which was dealt with above. */
mpfr_set_ui (mpc_realref (z), 0, MPC_RND_RE (rnd));
/* Note: fix_sign only does something when y is an integer,
then necessarily y = 1 or 3 (mod 4), and in that case the
sign of Im(x) is irrelevant. */
fix_sign (z, sign_rex, 0, mpc_realref (y));
ret = MPC_INEX(0, ret);
}
else
ret = MPC_INEX(mpfr_set_ui (mpc_realref(z), 0, MPC_RND_RE(rnd)), ret);
}
else
ret = mpc_set (z, u, rnd);
exact:
mpc_clear (t);
mpc_clear (u);
/* restore underflow and overflow flags from MPFR */
if (saved_underflow)
mpfr_set_underflow ();
if (saved_overflow)
mpfr_set_overflow ();
end:
return ret;
}
int
mpc_div (mpc_ptr a, mpc_srcptr b, mpc_srcptr c, mpc_rnd_t rnd)
{
int ok_re = 0, ok_im = 0;
mpc_t res, c_conj;
mpfr_t q;
mpfr_prec_t prec;
int inex, inexact_prod, inexact_norm, inexact_re, inexact_im, loops = 0;
int underflow_norm, overflow_norm, underflow_prod, overflow_prod;
int underflow_re = 0, overflow_re = 0, underflow_im = 0, overflow_im = 0;
mpfr_rnd_t rnd_re = MPC_RND_RE (rnd), rnd_im = MPC_RND_IM (rnd);
int saved_underflow, saved_overflow;
int tmpsgn;
mpfr_exp_t e, emin, emax, emid; /* for scaling of exponents */
mpc_t b_scaled, c_scaled;
mpfr_t b_re, b_im, c_re, c_im;
/* According to the C standard G.3, there are three types of numbers: */
/* finite (both parts are usual real numbers; contains 0), infinite */
/* (at least one part is a real infinity) and all others; the latter */
/* are numbers containing a nan, but no infinity, and could reasonably */
/* be called nan. */
/* By G.5.1.4, infinite/finite=infinite; finite/infinite=0; */
/* all other divisions that are not finite/finite return nan+i*nan. */
/* Division by 0 could be handled by the following case of division by */
/* a real; we handle it separately instead. */
if (mpc_zero_p (c)) /* both Re(c) and Im(c) are zero */
return mpc_div_zero (a, b, c, rnd);
else if (mpc_inf_p (b) && mpc_fin_p (c)) /* either Re(b) or Im(b) is infinite
and both Re(c) and Im(c) are ordinary */
return mpc_div_inf_fin (a, b, c);
else if (mpc_fin_p (b) && mpc_inf_p (c))
return mpc_div_fin_inf (a, b, c);
else if (!mpc_fin_p (b) || !mpc_fin_p (c)) {
mpc_set_nan (a);
return MPC_INEX (0, 0);
}
else if (mpfr_zero_p(mpc_imagref(c)))
return mpc_div_real (a, b, c, rnd);
else if (mpfr_zero_p(mpc_realref(c)))
return mpc_div_imag (a, b, c, rnd);
prec = MPC_MAX_PREC(a);
mpc_init2 (res, 2);
mpfr_init (q);
/* compute scaling of exponents: none of Re(c) and Im(c) can be zero,
but one of Re(b) or Im(b) could be zero */
e = mpfr_get_exp (mpc_realref (c));
emin = emax = e;
e = mpfr_get_exp (mpc_imagref (c));
if (e > emax)
emax = e;
else if (e < emin)
emin = e;
if (!mpfr_zero_p (mpc_realref (b)))
{
e = mpfr_get_exp (mpc_realref (b));
if (e > emax)
emax = e;
else if (e < emin)
emin = e;
}
if (!mpfr_zero_p (mpc_imagref (b)))
{
e = mpfr_get_exp (mpc_imagref (b));
if (e > emax)
emax = e;
else if (e < emin)
emin = e;
}
/* all input exponents are in [emin, emax] */
emid = emin / 2 + emax / 2;
/* scale the inputs */
b_re[0] = mpc_realref (b)[0];
if (!mpfr_zero_p (mpc_realref (b)))
MPFR_EXP(b_re) = MPFR_EXP(mpc_realref (b)) - emid;
b_im[0] = mpc_imagref (b)[0];
if (!mpfr_zero_p (mpc_imagref (b)))
MPFR_EXP(b_im) = MPFR_EXP(mpc_imagref (b)) - emid;
c_re[0] = mpc_realref (c)[0];
MPFR_EXP(c_re) = MPFR_EXP(mpc_realref (c)) - emid;
c_im[0] = mpc_imagref (c)[0];
MPFR_EXP(c_im) = MPFR_EXP(mpc_imagref (c)) - emid;
/* create the scaled inputs without allocating new memory */
mpc_realref (b_scaled)[0] = b_re[0];
mpc_imagref (b_scaled)[0] = b_im[0];
mpc_realref (c_scaled)[0] = c_re[0];
mpc_imagref (c_scaled)[0] = c_im[0];
/* create the conjugate of c in c_conj without allocating new memory */
mpc_realref (c_conj)[0] = mpc_realref (c_scaled)[0];
mpc_imagref (c_conj)[0] = mpc_imagref (c_scaled)[0];
MPFR_CHANGE_SIGN (mpc_imagref (c_conj));
/* save the underflow or overflow flags from MPFR */
saved_underflow = mpfr_underflow_p ();
saved_overflow = mpfr_overflow_p ();
do {
loops ++;
prec += loops <= 2 ? mpc_ceil_log2 (prec) + 5 : prec / 2;
mpc_set_prec (res, prec);
mpfr_set_prec (q, prec);
/* first compute norm(c_scaled) */
mpfr_clear_underflow ();
mpfr_clear_overflow ();
inexact_norm = mpc_norm (q, c_scaled, MPFR_RNDU);
underflow_norm = mpfr_underflow_p ();
overflow_norm = mpfr_overflow_p ();
if (underflow_norm)
mpfr_set_ui (q, 0ul, MPFR_RNDN);
/* to obtain divisions by 0 later on */
/* now compute b_scaled*conjugate(c_scaled) */
mpfr_clear_underflow ();
mpfr_clear_overflow ();
inexact_prod = mpc_mul (res, b_scaled, c_conj, MPC_RNDZZ);
inexact_re = MPC_INEX_RE (inexact_prod);
inexact_im = MPC_INEX_IM (inexact_prod);
underflow_prod = mpfr_underflow_p ();
overflow_prod = mpfr_overflow_p ();
/* unfortunately, does not distinguish between under-/overflow
in real or imaginary parts
hopefully, the side-effects of mpc_mul do indeed raise the
mpfr exceptions */
if (overflow_prod) {
/* FIXME: in case overflow_norm is also true, the code below is wrong,
since the after division by the norm, we might end up with finite
real and/or imaginary parts. A workaround would be to scale the
inputs (in case the exponents are within the same range). */
int isinf = 0;
/* determine if the real part of res is the maximum or the minimum
representable number */
tmpsgn = mpfr_sgn (mpc_realref(res));
if (tmpsgn > 0)
{
mpfr_nextabove (mpc_realref(res));
isinf = mpfr_inf_p (mpc_realref(res));
mpfr_nextbelow (mpc_realref(res));
}
else if (tmpsgn < 0)
{
mpfr_nextbelow (mpc_realref(res));
isinf = mpfr_inf_p (mpc_realref(res));
mpfr_nextabove (mpc_realref(res));
}
if (isinf)
{
mpfr_set_inf (mpc_realref(res), tmpsgn);
overflow_re = 1;
}
/* same for the imaginary part */
tmpsgn = mpfr_sgn (mpc_imagref(res));
isinf = 0;
if (tmpsgn > 0)
{
mpfr_nextabove (mpc_imagref(res));
isinf = mpfr_inf_p (mpc_imagref(res));
mpfr_nextbelow (mpc_imagref(res));
}
else if (tmpsgn < 0)
{
mpfr_nextbelow (mpc_imagref(res));
isinf = mpfr_inf_p (mpc_imagref(res));
mpfr_nextabove (mpc_imagref(res));
}
if (isinf)
{
mpfr_set_inf (mpc_imagref(res), tmpsgn);
overflow_im = 1;
}
mpc_set (a, res, rnd);
goto end;
}
/* divide the product by the norm */
if (inexact_norm == 0 && (inexact_re == 0 || inexact_im == 0)) {
/* The division has good chances to be exact in at least one part. */
/* Since this can cause problems when not rounding to the nearest, */
/* we use the division code of mpfr, which handles the situation. */
mpfr_clear_underflow ();
mpfr_clear_overflow ();
inexact_re |= mpfr_div (mpc_realref (res), mpc_realref (res), q, MPFR_RNDZ);
underflow_re = mpfr_underflow_p ();
overflow_re = mpfr_overflow_p ();
ok_re = !inexact_re || underflow_re || overflow_re
|| mpfr_can_round (mpc_realref (res), prec - 4, MPFR_RNDN,
MPFR_RNDZ, MPC_PREC_RE(a) + (rnd_re == MPFR_RNDN));
if (ok_re) /* compute imaginary part */ {
mpfr_clear_underflow ();
mpfr_clear_overflow ();
inexact_im |= mpfr_div (mpc_imagref (res), mpc_imagref (res), q, MPFR_RNDZ);
underflow_im = mpfr_underflow_p ();
overflow_im = mpfr_overflow_p ();
ok_im = !inexact_im || underflow_im || overflow_im
|| mpfr_can_round (mpc_imagref (res), prec - 4, MPFR_RNDN,
MPFR_RNDZ, MPC_PREC_IM(a) + (rnd_im == MPFR_RNDN));
}
}
else {
/* The division is inexact, so for efficiency reasons we invert q */
/* only once and multiply by the inverse. */
if (mpfr_ui_div (q, 1ul, q, MPFR_RNDZ) || inexact_norm) {
/* if 1/q is inexact, the approximations of the real and
imaginary part below will be inexact, unless RE(res)
or IM(res) is zero */
inexact_re |= !mpfr_zero_p (mpc_realref (res));
inexact_im |= !mpfr_zero_p (mpc_imagref (res));
}
mpfr_clear_underflow ();
mpfr_clear_overflow ();
inexact_re |= mpfr_mul (mpc_realref (res), mpc_realref (res), q, MPFR_RNDZ);
underflow_re = mpfr_underflow_p ();
overflow_re = mpfr_overflow_p ();
ok_re = !inexact_re || underflow_re || overflow_re
|| mpfr_can_round (mpc_realref (res), prec - 4, MPFR_RNDN,
MPFR_RNDZ, MPC_PREC_RE(a) + (rnd_re == MPFR_RNDN));
if (ok_re) /* compute imaginary part */ {
mpfr_clear_underflow ();
mpfr_clear_overflow ();
inexact_im |= mpfr_mul (mpc_imagref (res), mpc_imagref (res), q, MPFR_RNDZ);
underflow_im = mpfr_underflow_p ();
overflow_im = mpfr_overflow_p ();
ok_im = !inexact_im || underflow_im || overflow_im
|| mpfr_can_round (mpc_imagref (res), prec - 4, MPFR_RNDN,
MPFR_RNDZ, MPC_PREC_IM(a) + (rnd_im == MPFR_RNDN));
}
}
} while ((!ok_re || !ok_im) && !underflow_norm && !overflow_norm
&& !underflow_prod && !overflow_prod);
inex = mpc_set (a, res, rnd);
inexact_re = MPC_INEX_RE (inex);
inexact_im = MPC_INEX_IM (inex);
end:
/* fix values and inexact flags in case of overflow/underflow */
/* FIXME: heuristic, certainly does not cover all cases */
if (overflow_re || (underflow_norm && !underflow_prod)) {
mpfr_set_inf (mpc_realref (a), mpfr_sgn (mpc_realref (res)));
inexact_re = mpfr_sgn (mpc_realref (res));
}
else if (underflow_re || (overflow_norm && !overflow_prod)) {
inexact_re = mpfr_signbit (mpc_realref (res)) ? 1 : -1;
mpfr_set_zero (mpc_realref (a), -inexact_re);
}
if (overflow_im || (underflow_norm && !underflow_prod)) {
mpfr_set_inf (mpc_imagref (a), mpfr_sgn (mpc_imagref (res)));
inexact_im = mpfr_sgn (mpc_imagref (res));
}
else if (underflow_im || (overflow_norm && !overflow_prod)) {
inexact_im = mpfr_signbit (mpc_imagref (res)) ? 1 : -1;
mpfr_set_zero (mpc_imagref (a), -inexact_im);
}
mpc_clear (res);
mpfr_clear (q);
/* restore underflow and overflow flags from MPFR */
if (saved_underflow)
mpfr_set_underflow ();
if (saved_overflow)
mpfr_set_overflow ();
return MPC_INEX (inexact_re, inexact_im);
}
/* Put in z the value of x^y, rounded according to 'rnd'.
Return the inexact flag in [0, 10]. */
int
mpc_pow (mpc_ptr z, mpc_srcptr x, mpc_srcptr y, mpc_rnd_t rnd)
{
int ret = -2, loop, x_real, y_real, z_real = 0, z_imag = 0;
mpc_t t, u;
mp_prec_t p, q, pr, pi, maxprec;
long Q;
x_real = mpfr_zero_p (MPC_IM(x));
y_real = mpfr_zero_p (MPC_IM(y));
if (y_real && mpfr_zero_p (MPC_RE(y))) /* case y zero */
{
if (x_real && mpfr_zero_p (MPC_RE(x))) /* 0^0 = NaN +i*NaN */
{
mpfr_set_nan (MPC_RE(z));
mpfr_set_nan (MPC_IM(z));
return 0;
}
else /* x^0 = 1 +/- i*0 even for x=NaN see algorithms.tex for the
sign of zero */
{
mpfr_t n;
int inex, cx1;
int sign_zi;
/* cx1 < 0 if |x| < 1
cx1 = 0 if |x| = 1
cx1 > 0 if |x| > 1
*/
mpfr_init (n);
inex = mpc_norm (n, x, GMP_RNDN);
cx1 = mpfr_cmp_ui (n, 1);
if (cx1 == 0 && inex != 0)
cx1 = -inex;
sign_zi = (cx1 < 0 && mpfr_signbit (MPC_IM (y)) == 0)
|| (cx1 == 0
&& mpfr_signbit (MPC_IM (x)) != mpfr_signbit (MPC_RE (y)))
|| (cx1 > 0 && mpfr_signbit (MPC_IM (y)));
/* warning: mpc_set_ui_ui does not set Im(z) to -0 if Im(rnd)=RNDD */
ret = mpc_set_ui_ui (z, 1, 0, rnd);
if (MPC_RND_IM (rnd) == GMP_RNDD || sign_zi)
mpc_conj (z, z, MPC_RNDNN);
mpfr_clear (n);
return ret;
}
}
if (mpfr_nan_p (MPC_RE(x)) || mpfr_nan_p (MPC_IM(x)) ||
mpfr_nan_p (MPC_RE(y)) || mpfr_nan_p (MPC_IM(y)) ||
mpfr_inf_p (MPC_RE(x)) || mpfr_inf_p (MPC_IM(x)) ||
mpfr_inf_p (MPC_RE(y)) || mpfr_inf_p (MPC_IM(y)))
{
/* special values: exp(y*log(x)) */
mpc_init2 (u, 2);
mpc_log (u, x, MPC_RNDNN);
mpc_mul (u, u, y, MPC_RNDNN);
ret = mpc_exp (z, u, rnd);
mpc_clear (u);
goto end;
}
if (x_real) /* case x real */
{
if (mpfr_zero_p (MPC_RE(x))) /* x is zero */
{
/* special values: exp(y*log(x)) */
mpc_init2 (u, 2);
mpc_log (u, x, MPC_RNDNN);
mpc_mul (u, u, y, MPC_RNDNN);
ret = mpc_exp (z, u, rnd);
mpc_clear (u);
goto end;
}
/* Special case 1^y = 1 */
if (mpfr_cmp_ui (MPC_RE(x), 1) == 0)
{
int s1, s2;
s1 = mpfr_signbit (MPC_RE (y));
s2 = mpfr_signbit (MPC_IM (x));
ret = mpc_set_ui (z, +1, rnd);
/* the sign of the zero imaginary part is known in some cases (see
algorithm.tex). In such cases we have
(x +s*0i)^(y+/-0i) = x^y + s*sign(y)*0i
where s = +/-1. We extend here this rule to fix the sign of the
zero part.
Note that the sign must also be set explicitly when rnd=RNDD
because mpfr_set_ui(z_i, 0, rnd) always sets z_i to +0.
*/
if (MPC_RND_IM (rnd) == GMP_RNDD || s1 != s2)
mpc_conj (z, z, MPC_RNDNN);
goto end;
}
/* x^y is real when:
(a) x is real and y is integer
(b) x is real non-negative and y is real */
if (y_real && (mpfr_integer_p (MPC_RE(y)) ||
mpfr_cmp_ui (MPC_RE(x), 0) >= 0))
{
int s1, s2;
s1 = mpfr_signbit (MPC_RE (y));
s2 = mpfr_signbit (MPC_IM (x));
ret = mpfr_pow (MPC_RE(z), MPC_RE(x), MPC_RE(y), MPC_RND_RE(rnd));
ret = MPC_INEX(ret, mpfr_set_ui (MPC_IM(z), 0, MPC_RND_IM(rnd)));
/* the sign of the zero imaginary part is known in some cases
(see algorithm.tex). In such cases we have (x +s*0i)^(y+/-0i)
= x^y + s*sign(y)*0i where s = +/-1.
We extend here this rule to fix the sign of the zero part.
Note that the sign must also be set explicitly when rnd=RNDD
because mpfr_set_ui(z_i, 0, rnd) always sets z_i to +0.
*/
if (MPC_RND_IM(rnd) == GMP_RNDD || s1 != s2)
mpfr_neg (MPC_IM(z), MPC_IM(z), MPC_RND_IM(rnd));
goto end;
}
/* (-1)^(n+I*t) is real for n integer and t real */
if (mpfr_cmp_si (MPC_RE(x), -1) == 0 && mpfr_integer_p (MPC_RE(y)))
z_real = 1;
/* for x real, x^y is imaginary when:
(a) x is negative and y is half-an-integer
(b) x = -1 and Re(y) is half-an-integer
*/
if (mpfr_cmp_ui (MPC_RE(x), 0) < 0 && is_odd (MPC_RE(y), 1) &&
(y_real || mpfr_cmp_si (MPC_RE(x), -1) == 0))
z_imag = 1;
}
else /* x non real */
/* I^(t*I) and (-I)^(t*I) are real for t real,
I^(n+t*I) and (-I)^(n+t*I) are real for n even and t real, and
I^(n+t*I) and (-I)^(n+t*I) are imaginary for n odd and t real
(s*I)^n is real for n even and imaginary for n odd */
if ((mpc_cmp_si_si (x, 0, 1) == 0 || mpc_cmp_si_si (x, 0, -1) == 0 ||
(mpfr_cmp_ui (MPC_RE(x), 0) == 0 && y_real)) &&
mpfr_integer_p (MPC_RE(y)))
{ /* x is I or -I, and Re(y) is an integer */
if (is_odd (MPC_RE(y), 0))
z_imag = 1; /* Re(y) odd: z is imaginary */
else
z_real = 1; /* Re(y) even: z is real */
}
else /* (t+/-t*I)^(2n) is imaginary for n odd and real for n even */
if (mpfr_cmpabs (MPC_RE(x), MPC_IM(x)) == 0 && y_real &&
mpfr_integer_p (MPC_RE(y)) && is_odd (MPC_RE(y), 0) == 0)
{
if (is_odd (MPC_RE(y), -1)) /* y/2 is odd */
z_imag = 1;
else
z_real = 1;
}
/* first bound |Re(y log(x))|, |Im(y log(x)| < 2^q */
mpc_init2 (t, 64);
mpc_log (t, x, MPC_RNDNN);
mpc_mul (t, t, y, MPC_RNDNN);
/* the default maximum exponent for MPFR is emax=2^30-1, thus if
t > log(2^emax) = emax*log(2), then exp(t) will overflow */
if (mpfr_cmp_ui_2exp (MPC_RE(t), 372130558, 1) > 0)
goto overflow;
/* the default minimum exponent for MPFR is emin=-2^30+1, thus the
smallest representable value is 2^(emin-1), and if
t < log(2^(emin-1)) = (emin-1)*log(2), then exp(t) will underflow */
if (mpfr_cmp_si_2exp (MPC_RE(t), -372130558, 1) < 0)
goto underflow;
q = mpfr_get_exp (MPC_RE(t)) > 0 ? mpfr_get_exp (MPC_RE(t)) : 0;
if (mpfr_get_exp (MPC_IM(t)) > (mp_exp_t) q)
q = mpfr_get_exp (MPC_IM(t));
pr = mpfr_get_prec (MPC_RE(z));
pi = mpfr_get_prec (MPC_IM(z));
p = (pr > pi) ? pr : pi;
p += 11; /* experimentally, seems to give less than 10% of failures in
Ziv's strategy */
mpc_init2 (u, p);
pr += MPC_RND_RE(rnd) == GMP_RNDN;
pi += MPC_RND_IM(rnd) == GMP_RNDN;
maxprec = MPFR_PREC(MPC_RE(z));
if (MPFR_PREC(MPC_IM(z)) > maxprec)
maxprec = MPFR_PREC(MPC_IM(z));
for (loop = 0;; loop++)
{
mp_exp_t dr, di;
if (p + q > 64) /* otherwise we reuse the initial approximation
t of y*log(x), avoiding two computations */
{
mpc_set_prec (t, p + q);
mpc_log (t, x, MPC_RNDNN);
mpc_mul (t, t, y, MPC_RNDNN);
}
mpc_exp (u, t, MPC_RNDNN);
/* Since the error bound is global, we have to take into account the
exponent difference between the real and imaginary parts. We assume
either the real or the imaginary part of u is not zero.
*/
dr = mpfr_zero_p (MPC_RE(u)) ? mpfr_get_exp (MPC_IM(u))
: mpfr_get_exp (MPC_RE(u));
di = mpfr_zero_p (MPC_IM(u)) ? dr : mpfr_get_exp (MPC_IM(u));
if (dr > di)
{
di = dr - di;
dr = 0;
}
else
{
dr = di - dr;
di = 0;
}
/* the term -3 takes into account the factor 4 in the complex error
(see algorithms.tex) plus one due to the exponent difference: if
z = a + I*b, where the relative error on z is at most 2^(-p), and
EXP(a) = EXP(b) + k, the relative error on b is at most 2^(k-p) */
if ((z_imag || mpfr_can_round (MPC_RE(u), p - 3 - dr, GMP_RNDN, GMP_RNDZ, pr)) &&
(z_real || mpfr_can_round (MPC_IM(u), p - 3 - di, GMP_RNDN, GMP_RNDZ, pi)))
break;
/* if Re(u) is not known to be zero, assume it is a normal number, i.e.,
neither zero, Inf or NaN, otherwise we might enter an infinite loop */
MPC_ASSERT (z_imag || mpfr_number_p (MPC_RE(u)));
/* idem for Im(u) */
MPC_ASSERT (z_real || mpfr_number_p (MPC_IM(u)));
if (ret == -2) /* we did not yet call mpc_pow_exact, or it aborted
because intermediate computations had > maxprec bits */
{
/* check exact cases (see algorithms.tex) */
if (y_real)
{
maxprec *= 2;
ret = mpc_pow_exact (z, x, MPC_RE(y), rnd, maxprec);
if (ret != -1 && ret != -2)
goto exact;
}
p += dr + di + 64;
}
else
p += p / 2;
mpc_set_prec (t, p + q);
mpc_set_prec (u, p);
}
if (z_real)
{
/* When the result is real (see algorithm.tex for details),
Im(x^y) =
+ sign(imag(y))*0i, if |x| > 1
+ sign(imag(x))*sign(real(y))*0i, if |x| = 1
- sign(imag(y))*0i, if |x| < 1
*/
mpfr_t n;
int inex, cx1;
int sign_zi;
/* cx1 < 0 if |x| < 1
cx1 = 0 if |x| = 1
cx1 > 0 if |x| > 1
*/
mpfr_init (n);
inex = mpc_norm (n, x, GMP_RNDN);
cx1 = mpfr_cmp_ui (n, 1);
if (cx1 == 0 && inex != 0)
cx1 = -inex;
sign_zi = (cx1 < 0 && mpfr_signbit (MPC_IM (y)) == 0)
|| (cx1 == 0
&& mpfr_signbit (MPC_IM (x)) != mpfr_signbit (MPC_RE (y)))
|| (cx1 > 0 && mpfr_signbit (MPC_IM (y)));
ret = mpfr_set (MPC_RE(z), MPC_RE(u), MPC_RND_RE(rnd));
/* warning: mpfr_set_ui does not set Im(z) to -0 if Im(rnd) = RNDD */
ret = MPC_INEX (ret, mpfr_set_ui (MPC_IM (z), 0, MPC_RND_IM (rnd)));
if (MPC_RND_IM (rnd) == GMP_RNDD || sign_zi)
mpc_conj (z, z, MPC_RNDNN);
mpfr_clear (n);
}
else if (z_imag)
{
ret = mpfr_set (MPC_IM(z), MPC_IM(u), MPC_RND_IM(rnd));
ret = MPC_INEX(mpfr_set_ui (MPC_RE(z), 0, MPC_RND_RE(rnd)), ret);
}
else
ret = mpc_set (z, u, rnd);
exact:
mpc_clear (t);
mpc_clear (u);
end:
return ret;
underflow:
/* If we have an underflow, we know that |z| is too small to be
represented, but depending on arg(z), we should return +/-0 +/- I*0.
We assume t is the approximation of y*log(x), thus we want
exp(t) = exp(Re(t))+exp(I*Im(t)).
FIXME: this part of code is not 100% rigorous, since we don't consider
rounding errors.
*/
mpc_init2 (u, 64);
mpfr_const_pi (MPC_RE(u), GMP_RNDN);
mpfr_div_2exp (MPC_RE(u), MPC_RE(u), 1, GMP_RNDN); /* Pi/2 */
mpfr_remquo (MPC_RE(u), &Q, MPC_IM(t), MPC_RE(u), GMP_RNDN);
if (mpfr_sgn (MPC_RE(u)) < 0)
Q--; /* corresponds to positive remainder */
mpfr_set_ui (MPC_RE(z), 0, GMP_RNDN);
mpfr_set_ui (MPC_IM(z), 0, GMP_RNDN);
switch (Q & 3)
{
case 0: /* first quadrant: round to (+0 +0) */
ret = MPC_INEX(-1, -1);
break;
case 1: /* second quadrant: round to (-0 +0) */
mpfr_neg (MPC_RE(z), MPC_RE(z), GMP_RNDN);
ret = MPC_INEX(1, -1);
break;
case 2: /* third quadrant: round to (-0 -0) */
mpfr_neg (MPC_RE(z), MPC_RE(z), GMP_RNDN);
mpfr_neg (MPC_IM(z), MPC_IM(z), GMP_RNDN);
ret = MPC_INEX(1, 1);
break;
case 3: /* fourth quadrant: round to (+0 -0) */
mpfr_neg (MPC_IM(z), MPC_IM(z), GMP_RNDN);
ret = MPC_INEX(-1, 1);
break;
}
goto clear_t_and_u;
overflow:
/* If we have an overflow, we know that |z| is too large to be
represented, but depending on arg(z), we should return +/-Inf +/- I*Inf.
We assume t is the approximation of y*log(x), thus we want
exp(t) = exp(Re(t))+exp(I*Im(t)).
FIXME: this part of code is not 100% rigorous, since we don't consider
rounding errors.
*/
mpc_init2 (u, 64);
mpfr_const_pi (MPC_RE(u), GMP_RNDN);
mpfr_div_2exp (MPC_RE(u), MPC_RE(u), 1, GMP_RNDN); /* Pi/2 */
/* the quotient is rounded to the nearest integer in mpfr_remquo */
mpfr_remquo (MPC_RE(u), &Q, MPC_IM(t), MPC_RE(u), GMP_RNDN);
if (mpfr_sgn (MPC_RE(u)) < 0)
Q--; /* corresponds to positive remainder */
switch (Q & 3)
{
case 0: /* first quadrant */
mpfr_set_inf (MPC_RE(z), 1);
mpfr_set_inf (MPC_IM(z), 1);
ret = MPC_INEX(1, 1);
break;
case 1: /* second quadrant */
mpfr_set_inf (MPC_RE(z), -1);
mpfr_set_inf (MPC_IM(z), 1);
ret = MPC_INEX(-1, 1);
break;
case 2: /* third quadrant */
mpfr_set_inf (MPC_RE(z), -1);
mpfr_set_inf (MPC_IM(z), -1);
ret = MPC_INEX(-1, -1);
break;
case 3: /* fourth quadrant */
mpfr_set_inf (MPC_RE(z), 1);
mpfr_set_inf (MPC_IM(z), -1);
ret = MPC_INEX(1, -1);
break;
}
clear_t_and_u:
mpc_clear (t);
mpc_clear (u);
return ret;
}
