static void
pure_real_argument (void)
{
/* cosh(x -i*0) = cosh(x) +i*0 if x<0 */
/* cosh(x -i*0) = cosh(x) -i*0 if x>0 */
/* cosh(x +i*0) = cosh(x) -i*0 if x<0 */
/* cosh(x -i*0) = cosh(x) +i*0 if x>0 */
mpc_t u;
mpc_t z;
mpc_t cosh_z;
mpc_init2 (z, 2);
mpc_init2 (u, 100);
mpc_init2 (cosh_z, 100);
/* cosh(1 +i*0) = cosh(1) +i*0 */
mpc_set_ui_ui (z, 1, 0, MPC_RNDNN);
mpfr_cosh (MPC_RE (u), MPC_RE (z), GMP_RNDN);
mpfr_set_ui (MPC_IM (u), 0, GMP_RNDN);
mpc_cosh (cosh_z, z, MPC_RNDNN);
if (mpc_cmp (cosh_z, u) != 0 || mpfr_signbit (MPC_IM (cosh_z)))
TEST_FAILED ("mpc_cosh", z, cosh_z, u, MPC_RNDNN);
/* cosh(1 -i*0) = cosh(1) -i*0 */
mpc_conj (z, z, MPC_RNDNN);
mpc_conj (u, u, MPC_RNDNN);
mpc_cosh (cosh_z, z, MPC_RNDNN);
if (mpc_cmp (cosh_z, u) != 0 || !mpfr_signbit (MPC_IM (cosh_z)))
TEST_FAILED ("mpc_cosh", z, cosh_z, u, MPC_RNDNN);
/* cosh(-1 +i*0) = cosh(1) -i*0 */
mpc_neg (z, z, MPC_RNDNN);
mpc_cosh (cosh_z, z, MPC_RNDNN);
if (mpc_cmp (cosh_z, u) != 0 || !mpfr_signbit (MPC_IM (cosh_z)))
TEST_FAILED ("mpc_cosh", z, cosh_z, u, MPC_RNDNN);
/* cosh(-1 -i*0) = cosh(1) +i*0 */
mpc_conj (z, z, MPC_RNDNN);
mpc_conj (u, u, MPC_RNDNN);
mpc_cosh (cosh_z, z, MPC_RNDNN);
if (mpc_cmp (cosh_z, u) != 0 || mpfr_signbit (MPC_IM (cosh_z)))
TEST_FAILED ("mpc_cosh", z, cosh_z, u, MPC_RNDNN);
mpc_clear (cosh_z);
mpc_clear (z);
mpc_clear (u);
}
static void
pure_imaginary_argument (void)
{
/* cosh(+0 +i*y) = cos y +i*0*sin y */
/* cosh(-0 +i*y) = cos y -i*0*sin y */
mpc_t u;
mpc_t z;
mpc_t cosh_z;
mpc_init2 (z, 2);
mpc_init2 (u, 100);
mpc_init2 (cosh_z, 100);
/* cosh(+0 +i) = cos(1) + i*0 */
mpc_set_ui_ui (z, 0, 1, MPC_RNDNN);
mpfr_cos (MPC_RE (u), MPC_IM (z), GMP_RNDN);
mpfr_set_ui (MPC_IM (u), 0, GMP_RNDN);
mpc_cosh (cosh_z, z, MPC_RNDNN);
if (mpc_cmp (cosh_z, u) != 0 || mpfr_signbit (MPC_IM (cosh_z)))
TEST_FAILED ("mpc_cosh", z, cosh_z, u, MPC_RNDNN);
/* cosh(+0 -i) = cos(1) - i*0 */
mpc_conj (z, z, MPC_RNDNN);
mpc_conj (u, u, MPC_RNDNN);
mpc_cosh (cosh_z, z, MPC_RNDNN);
if (mpc_cmp (cosh_z, u) != 0 || !mpfr_signbit (MPC_IM (cosh_z)))
TEST_FAILED ("mpc_cosh", z, cosh_z, u, MPC_RNDNN);
/* cosh(-0 +i) = cos(1) - i*0 */
mpc_neg (z, z, MPC_RNDNN);
mpc_cosh (cosh_z, z, MPC_RNDNN);
if (mpc_cmp (cosh_z, u) != 0 || !mpfr_signbit (MPC_IM (cosh_z)))
TEST_FAILED ("mpc_cosh", z, cosh_z, u, MPC_RNDNN);
/* cosh(-0 -i) = cos(1) + i*0 */
mpc_conj (z, z, MPC_RNDNN);
mpc_conj (u, u, MPC_RNDNN);
mpc_cosh (cosh_z, z, MPC_RNDNN);
if (mpc_cmp (cosh_z, u) != 0 || mpfr_signbit (MPC_IM (cosh_z)))
TEST_FAILED ("mpc_cosh", z, cosh_z, u, MPC_RNDNN);
mpc_clear (cosh_z);
mpc_clear (z);
mpc_clear (u);
}
SEXP R_mpc_conj(SEXP x) {
if (!Rf_inherits(x, "mpc")) {
Rf_error("Invalid operand for conj.mpc");
}
mpc_t *z = (mpc_t *)malloc(sizeof(mpc_t));
mpc_t *z1 = (mpc_t *)R_ExternalPtrAddr(x);
mpc_init2(*z, mpc_get_prec(*z1));
mpc_conj(*z, *z1, Rmpc_get_rounding());
SEXP retVal = PROTECT(R_MakeExternalPtr((void *)z,
Rf_install("mpc ptr"), R_NilValue));
Rf_setAttrib(retVal, R_ClassSymbol, Rf_mkString("mpc"));
R_RegisterCFinalizerEx(retVal, mpcFinalizer, TRUE);
UNPROTECT(1);
return retVal;
}
static PyObject *
GMPy_MPC_Conjugate_Method(PyObject *self, PyObject *args)
{
MPC_Object *result;
CTXT_Object *context = NULL;
CHECK_CONTEXT(context);
if (!(result = GMPy_MPC_New(0, 0, context))) {
return NULL;
}
result->rc = mpc_conj(result->c, MPC(self), GET_MPC_ROUND(context));
GMPY_MPC_CLEANUP(result, context, "conjugate()");
return (PyObject*)result;
}
static void
reuse_bug (void)
{
mpc_t z1;
/* reuse bug found by Paul Zimmermann 20081021 */
mpc_init2 (z1, 2);
/* RE (z1^2) overflows, IM(z^2) = -0 */
mpfr_set_str (mpc_realref (z1), "0.11", 2, MPFR_RNDN);
mpfr_mul_2si (mpc_realref (z1), mpc_realref (z1), mpfr_get_emax (), MPFR_RNDN);
mpfr_set_ui (mpc_imagref (z1), 0, MPFR_RNDN);
mpc_conj (z1, z1, MPC_RNDNN);
mpc_sqr (z1, z1, MPC_RNDNN);
if (!mpfr_inf_p (mpc_realref (z1)) || mpfr_signbit (mpc_realref (z1))
||!mpfr_zero_p (mpc_imagref (z1)) || !mpfr_signbit (mpc_imagref (z1)))
{
printf ("Error: Regression, bug 20081021 reproduced\n");
MPC_OUT (z1);
exit (1);
}
mpc_clear (z1);
}
int
mpc_asin (mpc_ptr rop, mpc_srcptr op, mpc_rnd_t rnd)
{
mpfr_prec_t p, p_re, p_im, incr_p = 0;
mpfr_rnd_t rnd_re, rnd_im;
mpc_t z1;
int inex;
/* special values */
if (mpfr_nan_p (mpc_realref (op)) || mpfr_nan_p (mpc_imagref (op)))
{
if (mpfr_inf_p (mpc_realref (op)) || mpfr_inf_p (mpc_imagref (op)))
{
mpfr_set_nan (mpc_realref (rop));
mpfr_set_inf (mpc_imagref (rop), mpfr_signbit (mpc_imagref (op)) ? -1 : +1);
}
else if (mpfr_zero_p (mpc_realref (op)))
{
mpfr_set (mpc_realref (rop), mpc_realref (op), GMP_RNDN);
mpfr_set_nan (mpc_imagref (rop));
}
else
{
mpfr_set_nan (mpc_realref (rop));
mpfr_set_nan (mpc_imagref (rop));
}
return 0;
}
if (mpfr_inf_p (mpc_realref (op)) || mpfr_inf_p (mpc_imagref (op)))
{
int inex_re;
if (mpfr_inf_p (mpc_realref (op)))
{
int inf_im = mpfr_inf_p (mpc_imagref (op));
inex_re = set_pi_over_2 (mpc_realref (rop),
(mpfr_signbit (mpc_realref (op)) ? -1 : 1), MPC_RND_RE (rnd));
mpfr_set_inf (mpc_imagref (rop), (mpfr_signbit (mpc_imagref (op)) ? -1 : 1));
if (inf_im)
mpfr_div_2ui (mpc_realref (rop), mpc_realref (rop), 1, GMP_RNDN);
}
else
{
mpfr_set_zero (mpc_realref (rop), (mpfr_signbit (mpc_realref (op)) ? -1 : 1));
inex_re = 0;
mpfr_set_inf (mpc_imagref (rop), (mpfr_signbit (mpc_imagref (op)) ? -1 : 1));
}
return MPC_INEX (inex_re, 0);
}
/* pure real argument */
if (mpfr_zero_p (mpc_imagref (op)))
{
int inex_re;
int inex_im;
int s_im;
s_im = mpfr_signbit (mpc_imagref (op));
if (mpfr_cmp_ui (mpc_realref (op), 1) > 0)
{
if (s_im)
inex_im = -mpfr_acosh (mpc_imagref (rop), mpc_realref (op),
INV_RND (MPC_RND_IM (rnd)));
else
inex_im = mpfr_acosh (mpc_imagref (rop), mpc_realref (op),
MPC_RND_IM (rnd));
inex_re = set_pi_over_2 (mpc_realref (rop),
(mpfr_signbit (mpc_realref (op)) ? -1 : 1), MPC_RND_RE (rnd));
if (s_im)
mpc_conj (rop, rop, MPC_RNDNN);
}
else if (mpfr_cmp_si (mpc_realref (op), -1) < 0)
{
mpfr_t minus_op_re;
minus_op_re[0] = mpc_realref (op)[0];
MPFR_CHANGE_SIGN (minus_op_re);
if (s_im)
inex_im = -mpfr_acosh (mpc_imagref (rop), minus_op_re,
INV_RND (MPC_RND_IM (rnd)));
else
inex_im = mpfr_acosh (mpc_imagref (rop), minus_op_re,
MPC_RND_IM (rnd));
inex_re = set_pi_over_2 (mpc_realref (rop),
(mpfr_signbit (mpc_realref (op)) ? -1 : 1), MPC_RND_RE (rnd));
if (s_im)
mpc_conj (rop, rop, MPC_RNDNN);
}
else
{
inex_im = mpfr_set_ui (mpc_imagref (rop), 0, MPC_RND_IM (rnd));
if (s_im)
mpfr_neg (mpc_imagref (rop), mpc_imagref (rop), GMP_RNDN);
inex_re = mpfr_asin (mpc_realref (rop), mpc_realref (op), MPC_RND_RE (rnd));
}
return MPC_INEX (inex_re, inex_im);
}
/* pure imaginary argument */
if (mpfr_zero_p (mpc_realref (op)))
{
int inex_im;
int s;
s = mpfr_signbit (mpc_realref (op));
mpfr_set_ui (mpc_realref (rop), 0, GMP_RNDN);
if (s)
mpfr_neg (mpc_realref (rop), mpc_realref (rop), GMP_RNDN);
inex_im = mpfr_asinh (mpc_imagref (rop), mpc_imagref (op), MPC_RND_IM (rnd));
return MPC_INEX (0, inex_im);
}
/* regular complex: asin(z) = -i*log(i*z+sqrt(1-z^2)) */
p_re = mpfr_get_prec (mpc_realref(rop));
p_im = mpfr_get_prec (mpc_imagref(rop));
rnd_re = MPC_RND_RE(rnd);
rnd_im = MPC_RND_IM(rnd);
p = p_re >= p_im ? p_re : p_im;
mpc_init2 (z1, p);
while (1)
{
mpfr_exp_t ex, ey, err;
p += mpc_ceil_log2 (p) + 3 + incr_p; /* incr_p is zero initially */
incr_p = p / 2;
mpfr_set_prec (mpc_realref(z1), p);
mpfr_set_prec (mpc_imagref(z1), p);
/* z1 <- z^2 */
mpc_sqr (z1, op, MPC_RNDNN);
/* err(x) <= 1/2 ulp(x), err(y) <= 1/2 ulp(y) */
/* z1 <- 1-z1 */
ex = mpfr_get_exp (mpc_realref(z1));
mpfr_ui_sub (mpc_realref(z1), 1, mpc_realref(z1), GMP_RNDN);
mpfr_neg (mpc_imagref(z1), mpc_imagref(z1), GMP_RNDN);
ex = ex - mpfr_get_exp (mpc_realref(z1));
ex = (ex <= 0) ? 0 : ex;
/* err(x) <= 2^ex * ulp(x) */
ex = ex + mpfr_get_exp (mpc_realref(z1)) - p;
/* err(x) <= 2^ex */
ey = mpfr_get_exp (mpc_imagref(z1)) - p - 1;
/* err(y) <= 2^ey */
ex = (ex >= ey) ? ex : ey; /* err(x), err(y) <= 2^ex, i.e., the norm
of the error is bounded by |h|<=2^(ex+1/2) */
/* z1 <- sqrt(z1): if z1 = z + h, then sqrt(z1) = sqrt(z) + h/2/sqrt(t) */
ey = mpfr_get_exp (mpc_realref(z1)) >= mpfr_get_exp (mpc_imagref(z1))
? mpfr_get_exp (mpc_realref(z1)) : mpfr_get_exp (mpc_imagref(z1));
/* we have |z1| >= 2^(ey-1) thus 1/|z1| <= 2^(1-ey) */
mpc_sqrt (z1, z1, MPC_RNDNN);
ex = (2 * ex + 1) - 2 - (ey - 1); /* |h^2/4/|t| <= 2^ex */
ex = (ex + 1) / 2; /* ceil(ex/2) */
/* express ex in terms of ulp(z1) */
ey = mpfr_get_exp (mpc_realref(z1)) <= mpfr_get_exp (mpc_imagref(z1))
? mpfr_get_exp (mpc_realref(z1)) : mpfr_get_exp (mpc_imagref(z1));
ex = ex - ey + p;
/* take into account the rounding error in the mpc_sqrt call */
err = (ex <= 0) ? 1 : ex + 1;
/* err(x) <= 2^err * ulp(x), err(y) <= 2^err * ulp(y) */
/* z1 <- i*z + z1 */
ex = mpfr_get_exp (mpc_realref(z1));
ey = mpfr_get_exp (mpc_imagref(z1));
mpfr_sub (mpc_realref(z1), mpc_realref(z1), mpc_imagref(op), GMP_RNDN);
mpfr_add (mpc_imagref(z1), mpc_imagref(z1), mpc_realref(op), GMP_RNDN);
if (mpfr_cmp_ui (mpc_realref(z1), 0) == 0 || mpfr_cmp_ui (mpc_imagref(z1), 0) == 0)
continue;
ex -= mpfr_get_exp (mpc_realref(z1)); /* cancellation in x */
ey -= mpfr_get_exp (mpc_imagref(z1)); /* cancellation in y */
ex = (ex >= ey) ? ex : ey; /* maximum cancellation */
err += ex;
err = (err <= 0) ? 1 : err + 1; /* rounding error in sub/add */
/* z1 <- log(z1): if z1 = z + h, then log(z1) = log(z) + h/t with
|t| >= min(|z1|,|z|) */
ex = mpfr_get_exp (mpc_realref(z1));
ey = mpfr_get_exp (mpc_imagref(z1));
ex = (ex >= ey) ? ex : ey;
err += ex - p; /* revert to absolute error <= 2^err */
mpc_log (z1, z1, GMP_RNDN);
err -= ex - 1; /* 1/|t| <= 1/|z| <= 2^(1-ex) */
/* express err in terms of ulp(z1) */
ey = mpfr_get_exp (mpc_realref(z1)) <= mpfr_get_exp (mpc_imagref(z1))
? mpfr_get_exp (mpc_realref(z1)) : mpfr_get_exp (mpc_imagref(z1));
err = err - ey + p;
/* take into account the rounding error in the mpc_log call */
err = (err <= 0) ? 1 : err + 1;
/* z1 <- -i*z1 */
mpfr_swap (mpc_realref(z1), mpc_imagref(z1));
mpfr_neg (mpc_imagref(z1), mpc_imagref(z1), GMP_RNDN);
if (mpfr_can_round (mpc_realref(z1), p - err, GMP_RNDN, GMP_RNDZ,
p_re + (rnd_re == GMP_RNDN)) &&
mpfr_can_round (mpc_imagref(z1), p - err, GMP_RNDN, GMP_RNDZ,
p_im + (rnd_im == GMP_RNDN)))
break;
}
inex = mpc_set (rop, z1, rnd);
mpc_clear (z1);
return inex;
}
/* 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_sqrt (mpc_ptr a, mpc_srcptr b, mpc_rnd_t rnd)
{
int ok_w, ok_t = 0;
mpfr_t w, t;
mp_rnd_t rnd_w, rnd_t;
mp_prec_t prec_w, prec_t;
/* the rounding mode and the precision required for w and t, which can */
/* be either the real or the imaginary part of a */
mp_prec_t prec;
int inex_w, inex_t = 1, inex, loops = 0;
/* comparison of the real/imaginary part of b with 0 */
const int re_cmp = mpfr_cmp_ui (MPC_RE (b), 0);
const int im_cmp = mpfr_cmp_ui (MPC_IM (b), 0);
/* we need to know the sign of Im(b) when it is +/-0 */
const int im_sgn = mpfr_signbit (MPC_IM (b)) == 0? 0 : -1;
/* special values */
/* sqrt(x +i*Inf) = +Inf +I*Inf, even if x = NaN */
/* sqrt(x -i*Inf) = +Inf -I*Inf, even if x = NaN */
if (mpfr_inf_p (MPC_IM (b)))
{
mpfr_set_inf (MPC_RE (a), +1);
mpfr_set_inf (MPC_IM (a), im_sgn);
return MPC_INEX (0, 0);
}
if (mpfr_inf_p (MPC_RE (b)))
{
if (mpfr_signbit (MPC_RE (b)))
{
if (mpfr_number_p (MPC_IM (b)))
{
/* sqrt(-Inf +i*y) = +0 +i*Inf, when y positive */
/* sqrt(-Inf +i*y) = +0 -i*Inf, when y positive */
mpfr_set_ui (MPC_RE (a), 0, GMP_RNDN);
mpfr_set_inf (MPC_IM (a), im_sgn);
return MPC_INEX (0, 0);
}
else
{
/* sqrt(-Inf +i*NaN) = NaN +/-i*Inf */
mpfr_set_nan (MPC_RE (a));
mpfr_set_inf (MPC_IM (a), im_sgn);
return MPC_INEX (0, 0);
}
}
else
{
if (mpfr_number_p (MPC_IM (b)))
{
/* sqrt(+Inf +i*y) = +Inf +i*0, when y positive */
/* sqrt(+Inf +i*y) = +Inf -i*0, when y positive */
mpfr_set_inf (MPC_RE (a), +1);
mpfr_set_ui (MPC_IM (a), 0, GMP_RNDN);
if (im_sgn)
mpc_conj (a, a, MPC_RNDNN);
return MPC_INEX (0, 0);
}
else
{
/* sqrt(+Inf -i*Inf) = +Inf -i*Inf */
/* sqrt(+Inf +i*Inf) = +Inf +i*Inf */
/* sqrt(+Inf +i*NaN) = +Inf +i*NaN */
return mpc_set (a, b, rnd);
}
}
}
/* sqrt(x +i*NaN) = NaN +i*NaN, if x is not infinite */
/* sqrt(NaN +i*y) = NaN +i*NaN, if y is not infinite */
if (mpfr_nan_p (MPC_RE (b)) || mpfr_nan_p (MPC_IM (b)))
{
mpfr_set_nan (MPC_RE (a));
mpfr_set_nan (MPC_IM (a));
return MPC_INEX (0, 0);
}
/* purely real */
if (im_cmp == 0)
{
if (re_cmp == 0)
{
mpc_set_ui_ui (a, 0, 0, MPC_RNDNN);
if (im_sgn)
mpc_conj (a, a, MPC_RNDNN);
return MPC_INEX (0, 0);
}
else if (re_cmp > 0)
{
inex_w = mpfr_sqrt (MPC_RE (a), MPC_RE (b), MPC_RND_RE (rnd));
mpfr_set_ui (MPC_IM (a), 0, GMP_RNDN);
if (im_sgn)
mpc_conj (a, a, MPC_RNDNN);
return MPC_INEX (inex_w, 0);
}
else
{
mpfr_init2 (w, MPFR_PREC (MPC_RE (b)));
mpfr_neg (w, MPC_RE (b), GMP_RNDN);
if (im_sgn)
{
inex_w = -mpfr_sqrt (MPC_IM (a), w, INV_RND (MPC_RND_IM (rnd)));
mpfr_neg (MPC_IM (a), MPC_IM (a), GMP_RNDN);
}
else
inex_w = mpfr_sqrt (MPC_IM (a), w, MPC_RND_IM (rnd));
mpfr_set_ui (MPC_RE (a), 0, GMP_RNDN);
mpfr_clear (w);
return MPC_INEX (0, inex_w);
}
}
/* purely imaginary */
if (re_cmp == 0)
{
mpfr_t y;
y[0] = MPC_IM (b)[0];
/* If y/2 underflows, so does sqrt(y/2) */
mpfr_div_2ui (y, y, 1, GMP_RNDN);
if (im_cmp > 0)
{
inex_w = mpfr_sqrt (MPC_RE (a), y, MPC_RND_RE (rnd));
inex_t = mpfr_sqrt (MPC_IM (a), y, MPC_RND_IM (rnd));
}
else
{
mpfr_neg (y, y, GMP_RNDN);
inex_w = mpfr_sqrt (MPC_RE (a), y, MPC_RND_RE (rnd));
inex_t = -mpfr_sqrt (MPC_IM (a), y, INV_RND (MPC_RND_IM (rnd)));
mpfr_neg (MPC_IM (a), MPC_IM (a), GMP_RNDN);
}
return MPC_INEX (inex_w, inex_t);
}
prec = MPC_MAX_PREC(a);
mpfr_init (w);
mpfr_init (t);
if (re_cmp >= 0)
{
rnd_w = MPC_RND_RE (rnd);
prec_w = MPFR_PREC (MPC_RE (a));
rnd_t = MPC_RND_IM(rnd);
prec_t = MPFR_PREC (MPC_IM (a));
}
else
{
rnd_w = MPC_RND_IM(rnd);
prec_w = MPFR_PREC (MPC_IM (a));
rnd_t = MPC_RND_RE(rnd);
prec_t = MPFR_PREC (MPC_RE (a));
if (im_cmp < 0)
{
rnd_w = INV_RND(rnd_w);
rnd_t = INV_RND(rnd_t);
}
}
do
{
loops ++;
prec += (loops <= 2) ? mpc_ceil_log2 (prec) + 4 : prec / 2;
mpfr_set_prec (w, prec);
mpfr_set_prec (t, prec);
/* let b = x + iy */
/* w = sqrt ((|x| + sqrt (x^2 + y^2)) / 2), rounded down */
/* total error bounded by 3 ulps */
inex_w = mpc_abs (w, b, GMP_RNDD);
if (re_cmp < 0)
inex_w |= mpfr_sub (w, w, MPC_RE (b), GMP_RNDD);
else
inex_w |= mpfr_add (w, w, MPC_RE (b), GMP_RNDD);
inex_w |= mpfr_div_2ui (w, w, 1, GMP_RNDD);
inex_w |= mpfr_sqrt (w, w, GMP_RNDD);
ok_w = mpfr_can_round (w, (mp_exp_t) prec - 2, GMP_RNDD, GMP_RNDU,
prec_w + (rnd_w == GMP_RNDN));
if (!inex_w || ok_w)
{
/* t = y / 2w, rounded away */
/* total error bounded by 7 ulps */
const mp_rnd_t r = im_sgn ? GMP_RNDD : GMP_RNDU;
inex_t = mpfr_div (t, MPC_IM (b), w, r);
inex_t |= mpfr_div_2ui (t, t, 1, r);
ok_t = mpfr_can_round (t, (mp_exp_t) prec - 3, r, GMP_RNDZ,
prec_t + (rnd_t == GMP_RNDN));
/* As for w; since t was rounded away, we check whether rounding to 0
is possible. */
}
}
while ((inex_w && !ok_w) || (inex_t && !ok_t));
if (re_cmp > 0)
inex = MPC_INEX (mpfr_set (MPC_RE (a), w, MPC_RND_RE(rnd)),
mpfr_set (MPC_IM (a), t, MPC_RND_IM(rnd)));
else if (im_cmp > 0)
inex = MPC_INEX (mpfr_set (MPC_RE(a), t, MPC_RND_RE(rnd)),
mpfr_set (MPC_IM(a), w, MPC_RND_IM(rnd)));
else
inex = MPC_INEX (mpfr_neg (MPC_RE (a), t, MPC_RND_RE(rnd)),
mpfr_neg (MPC_IM (a), w, MPC_RND_IM(rnd)));
mpfr_clear (w);
mpfr_clear (t);
return inex;
}
int
mpc_sqr (mpc_ptr rop, mpc_srcptr op, mpc_rnd_t rnd)
{
int ok;
mpfr_t u, v;
mpfr_t x;
/* temporary variable to hold the real part of op,
needed in the case rop==op */
mpfr_prec_t prec;
int inex_re, inex_im, inexact;
mpfr_exp_t emin;
int saved_underflow;
/* special values: NaN and infinities */
if (!mpc_fin_p (op)) {
if (mpfr_nan_p (mpc_realref (op)) || mpfr_nan_p (mpc_imagref (op))) {
mpfr_set_nan (mpc_realref (rop));
mpfr_set_nan (mpc_imagref (rop));
}
else if (mpfr_inf_p (mpc_realref (op))) {
if (mpfr_inf_p (mpc_imagref (op))) {
mpfr_set_inf (mpc_imagref (rop),
MPFR_SIGN (mpc_realref (op)) * MPFR_SIGN (mpc_imagref (op)));
mpfr_set_nan (mpc_realref (rop));
}
else {
if (mpfr_zero_p (mpc_imagref (op)))
mpfr_set_nan (mpc_imagref (rop));
else
mpfr_set_inf (mpc_imagref (rop),
MPFR_SIGN (mpc_realref (op)) * MPFR_SIGN (mpc_imagref (op)));
mpfr_set_inf (mpc_realref (rop), +1);
}
}
else /* IM(op) is infinity, RE(op) is not */ {
if (mpfr_zero_p (mpc_realref (op)))
mpfr_set_nan (mpc_imagref (rop));
else
mpfr_set_inf (mpc_imagref (rop),
MPFR_SIGN (mpc_realref (op)) * MPFR_SIGN (mpc_imagref (op)));
mpfr_set_inf (mpc_realref (rop), -1);
}
return MPC_INEX (0, 0); /* exact */
}
prec = MPC_MAX_PREC(rop);
/* Check for real resp. purely imaginary number */
if (mpfr_zero_p (mpc_imagref(op))) {
int same_sign = mpfr_signbit (mpc_realref (op)) == mpfr_signbit (mpc_imagref (op));
inex_re = mpfr_sqr (mpc_realref(rop), mpc_realref(op), MPC_RND_RE(rnd));
inex_im = mpfr_set_ui (mpc_imagref(rop), 0ul, MPFR_RNDN);
if (!same_sign)
mpc_conj (rop, rop, MPC_RNDNN);
return MPC_INEX(inex_re, inex_im);
}
if (mpfr_zero_p (mpc_realref(op))) {
int same_sign = mpfr_signbit (mpc_realref (op)) == mpfr_signbit (mpc_imagref (op));
inex_re = -mpfr_sqr (mpc_realref(rop), mpc_imagref(op), INV_RND (MPC_RND_RE(rnd)));
mpfr_neg (mpc_realref(rop), mpc_realref(rop), MPFR_RNDN);
inex_im = mpfr_set_ui (mpc_imagref(rop), 0ul, MPFR_RNDN);
if (!same_sign)
mpc_conj (rop, rop, MPC_RNDNN);
return MPC_INEX(inex_re, inex_im);
}
if (rop == op)
{
mpfr_init2 (x, MPC_PREC_RE (op));
mpfr_set (x, op->re, MPFR_RNDN);
}
else
x [0] = op->re [0];
/* From here on, use x instead of op->re and safely overwrite rop->re. */
/* Compute real part of result. */
if (SAFE_ABS (mpfr_exp_t,
mpfr_get_exp (mpc_realref (op)) - mpfr_get_exp (mpc_imagref (op)))
> (mpfr_exp_t) MPC_MAX_PREC (op) / 2) {
/* If the real and imaginary parts of the argument have very different
exponents, it is not reasonable to use Karatsuba squaring; compute
exactly with the standard formulae instead, even if this means an
additional multiplication. Using the approach copied from mul, over-
and underflows are also handled correctly. */
inex_re = mpfr_fsss (rop->re, x, op->im, MPC_RND_RE (rnd));
}
else {
/* Karatsuba squaring: we compute the real part as (x+y)*(x-y) and the
imaginary part as 2*x*y, with a total of 2M instead of 2S+1M for the
naive algorithm, which computes x^2-y^2 and 2*y*y */
mpfr_init (u);
mpfr_init (v);
emin = mpfr_get_emin ();
do
{
prec += mpc_ceil_log2 (prec) + 5;
mpfr_set_prec (u, prec);
mpfr_set_prec (v, prec);
/* Let op = x + iy. We need u = x+y and v = x-y, rounded away. */
/* The error is bounded above by 1 ulp. */
/* We first let inexact be 1 if the real part is not computed */
/* exactly and determine the sign later. */
inexact = mpfr_add (u, x, mpc_imagref (op), MPFR_RNDA)
| mpfr_sub (v, x, mpc_imagref (op), MPFR_RNDA);
/* compute the real part as u*v, rounded away */
/* determine also the sign of inex_re */
if (mpfr_sgn (u) == 0 || mpfr_sgn (v) == 0) {
/* as we have rounded away, the result is exact */
mpfr_set_ui (mpc_realref (rop), 0, MPFR_RNDN);
inex_re = 0;
ok = 1;
}
else {
inexact |= mpfr_mul (u, u, v, MPFR_RNDA); /* error 5 */
if (mpfr_get_exp (u) == emin || mpfr_inf_p (u)) {
/* under- or overflow */
inex_re = mpfr_fsss (rop->re, x, op->im, MPC_RND_RE (rnd));
ok = 1;
}
else {
ok = (!inexact) | mpfr_can_round (u, prec - 3,
MPFR_RNDA, MPFR_RNDZ,
MPC_PREC_RE (rop) + (MPC_RND_RE (rnd) == MPFR_RNDN));
if (ok) {
inex_re = mpfr_set (mpc_realref (rop), u, MPC_RND_RE (rnd));
if (inex_re == 0)
/* remember that u was already rounded */
inex_re = inexact;
}
}
}
}
while (!ok);
mpfr_clear (u);
mpfr_clear (v);
}
saved_underflow = mpfr_underflow_p ();
mpfr_clear_underflow ();
inex_im = mpfr_mul (rop->im, x, op->im, MPC_RND_IM (rnd));
if (!mpfr_underflow_p ())
inex_im |= mpfr_mul_2ui (rop->im, rop->im, 1, MPC_RND_IM (rnd));
/* We must not multiply by 2 if rop->im has been set to the smallest
representable number. */
if (saved_underflow)
mpfr_set_underflow ();
if (rop == op)
mpfr_clear (x);
return MPC_INEX (inex_re, inex_im);
}
int
mpc_log (mpc_ptr rop, mpc_srcptr op, mpc_rnd_t rnd){
int ok, underflow = 0;
mpfr_srcptr x, y;
mpfr_t v, w;
mpfr_prec_t prec;
int loops;
int re_cmp, im_cmp;
int inex_re, inex_im;
int err;
mpfr_exp_t expw;
int sgnw;
/* special values: NaN and infinities */
if (!mpc_fin_p (op)) {
if (mpfr_nan_p (mpc_realref (op))) {
if (mpfr_inf_p (mpc_imagref (op)))
mpfr_set_inf (mpc_realref (rop), +1);
else
mpfr_set_nan (mpc_realref (rop));
mpfr_set_nan (mpc_imagref (rop));
inex_im = 0; /* Inf/NaN is exact */
}
else if (mpfr_nan_p (mpc_imagref (op))) {
if (mpfr_inf_p (mpc_realref (op)))
mpfr_set_inf (mpc_realref (rop), +1);
else
mpfr_set_nan (mpc_realref (rop));
mpfr_set_nan (mpc_imagref (rop));
inex_im = 0; /* Inf/NaN is exact */
}
else /* We have an infinity in at least one part. */ {
inex_im = mpfr_atan2 (mpc_imagref (rop), mpc_imagref (op), mpc_realref (op),
MPC_RND_IM (rnd));
mpfr_set_inf (mpc_realref (rop), +1);
}
return MPC_INEX(0, inex_im);
}
/* special cases: real and purely imaginary numbers */
re_cmp = mpfr_cmp_ui (mpc_realref (op), 0);
im_cmp = mpfr_cmp_ui (mpc_imagref (op), 0);
if (im_cmp == 0) {
if (re_cmp == 0) {
inex_im = mpfr_atan2 (mpc_imagref (rop), mpc_imagref (op), mpc_realref (op),
MPC_RND_IM (rnd));
mpfr_set_inf (mpc_realref (rop), -1);
inex_re = 0; /* -Inf is exact */
}
else if (re_cmp > 0) {
inex_re = mpfr_log (mpc_realref (rop), mpc_realref (op), MPC_RND_RE (rnd));
inex_im = mpfr_set (mpc_imagref (rop), mpc_imagref (op), MPC_RND_IM (rnd));
}
else {
/* op = x + 0*y; let w = -x = |x| */
int negative_zero;
mpfr_rnd_t rnd_im;
negative_zero = mpfr_signbit (mpc_imagref (op));
if (negative_zero)
rnd_im = INV_RND (MPC_RND_IM (rnd));
else
rnd_im = MPC_RND_IM (rnd);
w [0] = *mpc_realref (op);
MPFR_CHANGE_SIGN (w);
inex_re = mpfr_log (mpc_realref (rop), w, MPC_RND_RE (rnd));
inex_im = mpfr_const_pi (mpc_imagref (rop), rnd_im);
if (negative_zero) {
mpc_conj (rop, rop, MPC_RNDNN);
inex_im = -inex_im;
}
}
return MPC_INEX(inex_re, inex_im);
}
else if (re_cmp == 0) {
if (im_cmp > 0) {
inex_re = mpfr_log (mpc_realref (rop), mpc_imagref (op), MPC_RND_RE (rnd));
inex_im = mpfr_const_pi (mpc_imagref (rop), MPC_RND_IM (rnd));
/* division by 2 does not change the ternary flag */
mpfr_div_2ui (mpc_imagref (rop), mpc_imagref (rop), 1, GMP_RNDN);
}
else {
w [0] = *mpc_imagref (op);
MPFR_CHANGE_SIGN (w);
inex_re = mpfr_log (mpc_realref (rop), w, MPC_RND_RE (rnd));
inex_im = mpfr_const_pi (mpc_imagref (rop), INV_RND (MPC_RND_IM (rnd)));
/* division by 2 does not change the ternary flag */
mpfr_div_2ui (mpc_imagref (rop), mpc_imagref (rop), 1, GMP_RNDN);
mpfr_neg (mpc_imagref (rop), mpc_imagref (rop), GMP_RNDN);
inex_im = -inex_im; /* negate the ternary flag */
}
return MPC_INEX(inex_re, inex_im);
}
prec = MPC_PREC_RE(rop);
mpfr_init2 (w, 2);
/* let op = x + iy; log = 1/2 log (x^2 + y^2) + i atan2 (y, x) */
/* loop for the real part: 1/2 log (x^2 + y^2), fast, but unsafe */
/* implementation */
ok = 0;
for (loops = 1; !ok && loops <= 2; loops++) {
prec += mpc_ceil_log2 (prec) + 4;
mpfr_set_prec (w, prec);
mpc_abs (w, op, GMP_RNDN);
/* error 0.5 ulp */
if (mpfr_inf_p (w))
/* intermediate overflow; the logarithm may be representable.
Intermediate underflow is impossible. */
break;
mpfr_log (w, w, GMP_RNDN);
/* generic error of log: (2^(- exp(w)) + 0.5) ulp */
if (mpfr_zero_p (w))
/* impossible to round, switch to second algorithm */
break;
err = MPC_MAX (-mpfr_get_exp (w), 0) + 1;
/* number of lost digits */
ok = mpfr_can_round (w, prec - err, GMP_RNDN, GMP_RNDZ,
mpfr_get_prec (mpc_realref (rop)) + (MPC_RND_RE (rnd) == GMP_RNDN));
}
if (!ok) {
prec = MPC_PREC_RE(rop);
mpfr_init2 (v, 2);
/* compute 1/2 log (x^2 + y^2) = log |x| + 1/2 * log (1 + (y/x)^2)
if |x| >= |y|; otherwise, exchange x and y */
if (mpfr_cmpabs (mpc_realref (op), mpc_imagref (op)) >= 0) {
x = mpc_realref (op);
y = mpc_imagref (op);
}
else {
x = mpc_imagref (op);
y = mpc_realref (op);
}
do {
prec += mpc_ceil_log2 (prec) + 4;
mpfr_set_prec (v, prec);
mpfr_set_prec (w, prec);
mpfr_div (v, y, x, GMP_RNDD); /* error 1 ulp */
mpfr_sqr (v, v, GMP_RNDD);
/* generic error of multiplication:
1 + 2*1*(2+1*2^(1-prec)) <= 5.0625 since prec >= 6 */
mpfr_log1p (v, v, GMP_RNDD);
/* error 1 + 4*5.0625 = 21.25 , see algorithms.tex */
mpfr_div_2ui (v, v, 1, GMP_RNDD);
/* If the result is 0, then there has been an underflow somewhere. */
mpfr_abs (w, x, GMP_RNDN); /* exact */
mpfr_log (w, w, GMP_RNDN); /* error 0.5 ulp */
expw = mpfr_get_exp (w);
sgnw = mpfr_signbit (w);
mpfr_add (w, w, v, GMP_RNDN);
if (!sgnw) /* v is positive, so no cancellation;
error 22.25 ulp; error counts lost bits */
err = 5;
else
err = MPC_MAX (5 + mpfr_get_exp (v),
/* 21.25 ulp (v) rewritten in ulp (result, now in w) */
-1 + expw - mpfr_get_exp (w)
/* 0.5 ulp (previous w), rewritten in ulp (result) */
) + 2;
/* handle one special case: |x|=1, and (y/x)^2 underflows;
then 1/2*log(x^2+y^2) \approx 1/2*y^2 also underflows. */
if ( (mpfr_cmp_si (x, -1) == 0 || mpfr_cmp_ui (x, 1) == 0)
&& mpfr_zero_p (w))
underflow = 1;
} while (!underflow &&
!mpfr_can_round (w, prec - err, GMP_RNDN, GMP_RNDZ,
mpfr_get_prec (mpc_realref (rop)) + (MPC_RND_RE (rnd) == GMP_RNDN)));
mpfr_clear (v);
}
/* imaginary part */
inex_im = mpfr_atan2 (mpc_imagref (rop), mpc_imagref (op), mpc_realref (op),
MPC_RND_IM (rnd));
/* set the real part; cannot be done before if rop==op */
if (underflow)
/* create underflow in result */
inex_re = mpfr_set_ui_2exp (mpc_realref (rop), 1,
mpfr_get_emin_min () - 2, MPC_RND_RE (rnd));
else
inex_re = mpfr_set (mpc_realref (rop), w, MPC_RND_RE (rnd));
mpfr_clear (w);
return MPC_INEX(inex_re, inex_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;
}
int
mpc_atan (mpc_ptr rop, mpc_srcptr op, mpc_rnd_t rnd)
{
int s_re;
int s_im;
int inex_re;
int inex_im;
int inex;
inex_re = 0;
inex_im = 0;
s_re = mpfr_signbit (mpc_realref (op));
s_im = mpfr_signbit (mpc_imagref (op));
/* special values */
if (mpfr_nan_p (mpc_realref (op)) || mpfr_nan_p (mpc_imagref (op)))
{
if (mpfr_nan_p (mpc_realref (op)))
{
mpfr_set_nan (mpc_realref (rop));
if (mpfr_zero_p (mpc_imagref (op)) || mpfr_inf_p (mpc_imagref (op)))
{
mpfr_set_ui (mpc_imagref (rop), 0, GMP_RNDN);
if (s_im)
mpc_conj (rop, rop, MPC_RNDNN);
}
else
mpfr_set_nan (mpc_imagref (rop));
}
else
{
if (mpfr_inf_p (mpc_realref (op)))
{
inex_re = set_pi_over_2 (mpc_realref (rop), -s_re, MPC_RND_RE (rnd));
mpfr_set_ui (mpc_imagref (rop), 0, GMP_RNDN);
}
else
{
mpfr_set_nan (mpc_realref (rop));
mpfr_set_nan (mpc_imagref (rop));
}
}
return MPC_INEX (inex_re, 0);
}
if (mpfr_inf_p (mpc_realref (op)) || mpfr_inf_p (mpc_imagref (op)))
{
inex_re = set_pi_over_2 (mpc_realref (rop), -s_re, MPC_RND_RE (rnd));
mpfr_set_ui (mpc_imagref (rop), 0, GMP_RNDN);
if (s_im)
mpc_conj (rop, rop, GMP_RNDN);
return MPC_INEX (inex_re, 0);
}
/* pure real argument */
if (mpfr_zero_p (mpc_imagref (op)))
{
inex_re = mpfr_atan (mpc_realref (rop), mpc_realref (op), MPC_RND_RE (rnd));
mpfr_set_ui (mpc_imagref (rop), 0, GMP_RNDN);
if (s_im)
mpc_conj (rop, rop, GMP_RNDN);
return MPC_INEX (inex_re, 0);
}
/* pure imaginary argument */
if (mpfr_zero_p (mpc_realref (op)))
{
int cmp_1;
if (s_im)
cmp_1 = -mpfr_cmp_si (mpc_imagref (op), -1);
else
cmp_1 = mpfr_cmp_ui (mpc_imagref (op), +1);
if (cmp_1 < 0)
{
/* atan(+0+iy) = +0 +i*atanh(y), if |y| < 1
atan(-0+iy) = -0 +i*atanh(y), if |y| < 1 */
mpfr_set_ui (mpc_realref (rop), 0, GMP_RNDN);
if (s_re)
mpfr_neg (mpc_realref (rop), mpc_realref (rop), GMP_RNDN);
inex_im = mpfr_atanh (mpc_imagref (rop), mpc_imagref (op), MPC_RND_IM (rnd));
}
else if (cmp_1 == 0)
{
/* atan(+/-0+i) = NaN +i*inf
atan(+/-0-i) = NaN -i*inf */
mpfr_set_nan (mpc_realref (rop));
mpfr_set_inf (mpc_imagref (rop), s_im ? -1 : +1);
}
else
{
/* atan(+0+iy) = +pi/2 +i*atanh(1/y), if |y| > 1
atan(-0+iy) = -pi/2 +i*atanh(1/y), if |y| > 1 */
mpfr_rnd_t rnd_im, rnd_away;
mpfr_t y;
mpfr_prec_t p, p_im;
int ok;
rnd_im = MPC_RND_IM (rnd);
mpfr_init (y);
p_im = mpfr_get_prec (mpc_imagref (rop));
p = p_im;
/* a = o(1/y) with error(a) < 1 ulp(a)
b = o(atanh(a)) with error(b) < (1+2^{1+Exp(a)-Exp(b)}) ulp(b)
As |atanh (1/y)| > |1/y| we have Exp(a)-Exp(b) <=0 so, at most,
2 bits of precision are lost.
We round atanh(1/y) away from 0.
*/
do
{
p += mpc_ceil_log2 (p) + 2;
mpfr_set_prec (y, p);
rnd_away = s_im == 0 ? GMP_RNDU : GMP_RNDD;
inex_im = mpfr_ui_div (y, 1, mpc_imagref (op), rnd_away);
/* FIXME: should we consider the case with unreasonably huge
precision prec(y)>3*exp_min, where atanh(1/Im(op)) could be
representable while 1/Im(op) underflows ?
This corresponds to |y| = 0.5*2^emin, in which case the
result may be wrong. */
/* atanh cannot underflow: |atanh(x)| > |x| for |x| < 1 */
inex_im |= mpfr_atanh (y, y, rnd_away);
ok = inex_im == 0
|| mpfr_can_round (y, p - 2, rnd_away, GMP_RNDZ,
p_im + (rnd_im == GMP_RNDN));
} while (ok == 0);
inex_re = set_pi_over_2 (mpc_realref (rop), -s_re, MPC_RND_RE (rnd));
inex_im = mpfr_set (mpc_imagref (rop), y, rnd_im);
mpfr_clear (y);
}
return MPC_INEX (inex_re, inex_im);
}
/* regular number argument */
{
mpfr_t a, b, x, y;
mpfr_prec_t prec, p;
mpfr_exp_t err, expo;
int ok = 0;
mpfr_t minus_op_re;
mpfr_exp_t op_re_exp, op_im_exp;
mpfr_rnd_t rnd1, rnd2;
mpfr_inits2 (MPFR_PREC_MIN, a, b, x, y, (mpfr_ptr) 0);
/* real part: Re(arctan(x+i*y)) = [arctan2(x,1-y) - arctan2(-x,1+y)]/2 */
minus_op_re[0] = mpc_realref (op)[0];
MPFR_CHANGE_SIGN (minus_op_re);
op_re_exp = mpfr_get_exp (mpc_realref (op));
op_im_exp = mpfr_get_exp (mpc_imagref (op));
prec = mpfr_get_prec (mpc_realref (rop)); /* result precision */
/* a = o(1-y) error(a) < 1 ulp(a)
b = o(atan2(x,a)) error(b) < [1+2^{3+Exp(x)-Exp(a)-Exp(b)}] ulp(b)
= kb ulp(b)
c = o(1+y) error(c) < 1 ulp(c)
d = o(atan2(-x,c)) error(d) < [1+2^{3+Exp(x)-Exp(c)-Exp(d)}] ulp(d)
= kd ulp(d)
e = o(b - d) error(e) < [1 + kb*2^{Exp(b}-Exp(e)}
+ kd*2^{Exp(d)-Exp(e)}] ulp(e)
error(e) < [1 + 2^{4+Exp(x)-Exp(a)-Exp(e)}
+ 2^{4+Exp(x)-Exp(c)-Exp(e)}] ulp(e)
because |atan(u)| < |u|
< [1 + 2^{5+Exp(x)-min(Exp(a),Exp(c))
-Exp(e)}] ulp(e)
f = e/2 exact
*/
/* p: working precision */
p = (op_im_exp > 0 || prec > SAFE_ABS (mpfr_prec_t, op_im_exp)) ? prec
: (prec - op_im_exp);
rnd1 = mpfr_sgn (mpc_realref (op)) > 0 ? GMP_RNDD : GMP_RNDU;
rnd2 = mpfr_sgn (mpc_realref (op)) < 0 ? GMP_RNDU : GMP_RNDD;
do
{
p += mpc_ceil_log2 (p) + 2;
mpfr_set_prec (a, p);
mpfr_set_prec (b, p);
mpfr_set_prec (x, p);
/* x = upper bound for atan (x/(1-y)). Since atan is increasing, we
need an upper bound on x/(1-y), i.e., a lower bound on 1-y for
x positive, and an upper bound on 1-y for x negative */
mpfr_ui_sub (a, 1, mpc_imagref (op), rnd1);
if (mpfr_sgn (a) == 0) /* y is near 1, thus 1+y is near 2, and
expo will be 1 or 2 below */
{
MPC_ASSERT (mpfr_cmp_ui (mpc_imagref(op), 1) == 0);
/* check for intermediate underflow */
err = 2; /* ensures err will be expo below */
}
else
err = mpfr_get_exp (a); /* err = Exp(a) with the notations above */
mpfr_atan2 (x, mpc_realref (op), a, GMP_RNDU);
/* b = lower bound for atan (-x/(1+y)): for x negative, we need a
lower bound on -x/(1+y), i.e., an upper bound on 1+y */
mpfr_add_ui (a, mpc_imagref(op), 1, rnd2);
/* if a is exactly zero, i.e., Im(op) = -1, then the error on a is 0,
and we can simply ignore the terms involving Exp(a) in the error */
if (mpfr_sgn (a) == 0)
{
MPC_ASSERT (mpfr_cmp_si (mpc_imagref(op), -1) == 0);
/* check for intermediate underflow */
expo = err; /* will leave err unchanged below */
}
else
expo = mpfr_get_exp (a); /* expo = Exp(c) with the notations above */
mpfr_atan2 (b, minus_op_re, a, GMP_RNDD);
err = err < expo ? err : expo; /* err = min(Exp(a),Exp(c)) */
mpfr_sub (x, x, b, GMP_RNDU);
err = 5 + op_re_exp - err - mpfr_get_exp (x);
/* error is bounded by [1 + 2^err] ulp(e) */
err = err < 0 ? 1 : err + 1;
mpfr_div_2ui (x, x, 1, GMP_RNDU);
/* Note: using RND2=RNDD guarantees that if x is exactly representable
on prec + ... bits, mpfr_can_round will return 0 */
ok = mpfr_can_round (x, p - err, GMP_RNDU, GMP_RNDD,
prec + (MPC_RND_RE (rnd) == GMP_RNDN));
} while (ok == 0);
/* Imaginary part
Im(atan(x+I*y)) = 1/4 * [log(x^2+(1+y)^2) - log (x^2 +(1-y)^2)] */
prec = mpfr_get_prec (mpc_imagref (rop)); /* result precision */
/* a = o(1+y) error(a) < 1 ulp(a)
b = o(a^2) error(b) < 5 ulp(b)
c = o(x^2) error(c) < 1 ulp(c)
d = o(b+c) error(d) < 7 ulp(d)
e = o(log(d)) error(e) < [1 + 7*2^{2-Exp(e)}] ulp(e) = ke ulp(e)
f = o(1-y) error(f) < 1 ulp(f)
g = o(f^2) error(g) < 5 ulp(g)
h = o(c+f) error(h) < 7 ulp(h)
i = o(log(h)) error(i) < [1 + 7*2^{2-Exp(i)}] ulp(i) = ki ulp(i)
j = o(e-i) error(j) < [1 + ke*2^{Exp(e)-Exp(j)}
+ ki*2^{Exp(i)-Exp(j)}] ulp(j)
error(j) < [1 + 2^{Exp(e)-Exp(j)} + 2^{Exp(i)-Exp(j)}
+ 7*2^{3-Exp(j)}] ulp(j)
< [1 + 2^{max(Exp(e),Exp(i))-Exp(j)+1}
+ 7*2^{3-Exp(j)}] ulp(j)
k = j/4 exact
*/
err = 2;
p = prec; /* working precision */
do
{
p += mpc_ceil_log2 (p) + err;
mpfr_set_prec (a, p);
mpfr_set_prec (b, p);
mpfr_set_prec (y, p);
/* a = upper bound for log(x^2 + (1+y)^2) */
ROUND_AWAY (mpfr_add_ui (a, mpc_imagref (op), 1, MPFR_RNDA), a);
mpfr_sqr (a, a, GMP_RNDU);
mpfr_sqr (y, mpc_realref (op), GMP_RNDU);
mpfr_add (a, a, y, GMP_RNDU);
mpfr_log (a, a, GMP_RNDU);
/* b = lower bound for log(x^2 + (1-y)^2) */
mpfr_ui_sub (b, 1, mpc_imagref (op), GMP_RNDZ); /* round to zero */
mpfr_sqr (b, b, GMP_RNDZ);
/* we could write mpfr_sqr (y, mpc_realref (op), GMP_RNDZ) but it is
more efficient to reuse the value of y (x^2) above and subtract
one ulp */
mpfr_nextbelow (y);
mpfr_add (b, b, y, GMP_RNDZ);
mpfr_log (b, b, GMP_RNDZ);
mpfr_sub (y, a, b, GMP_RNDU);
if (mpfr_zero_p (y))
/* FIXME: happens when x and y have very different magnitudes;
could be handled more efficiently */
ok = 0;
else
{
expo = MPC_MAX (mpfr_get_exp (a), mpfr_get_exp (b));
expo = expo - mpfr_get_exp (y) + 1;
err = 3 - mpfr_get_exp (y);
/* error(j) <= [1 + 2^expo + 7*2^err] ulp(j) */
if (expo <= err) /* error(j) <= [1 + 2^{err+1}] ulp(j) */
err = (err < 0) ? 1 : err + 2;
else
err = (expo < 0) ? 1 : expo + 2;
mpfr_div_2ui (y, y, 2, GMP_RNDN);
MPC_ASSERT (!mpfr_zero_p (y));
/* FIXME: underflow. Since the main term of the Taylor series
in y=0 is 1/(x^2+1) * y, this means that y is very small
and/or x very large; but then the mpfr_zero_p (y) above
should be true. This needs a proof, or better yet,
special code. */
ok = mpfr_can_round (y, p - err, GMP_RNDU, GMP_RNDD,
prec + (MPC_RND_IM (rnd) == GMP_RNDN));
}
} while (ok == 0);
inex = mpc_set_fr_fr (rop, x, y, rnd);
mpfr_clears (a, b, x, y, (mpfr_ptr) 0);
return inex;
}
}
int
mpc_acos (mpc_ptr rop, mpc_srcptr op, mpc_rnd_t rnd)
{
int inex_re, inex_im, inex;
mpfr_prec_t p_re, p_im, p;
mpc_t z1;
mpfr_t pi_over_2;
mpfr_exp_t e1, e2;
mpfr_rnd_t rnd_im;
mpc_rnd_t rnd1;
inex_re = 0;
inex_im = 0;
/* special values */
if (mpfr_nan_p (mpc_realref (op)) || mpfr_nan_p (mpc_imagref (op)))
{
if (mpfr_inf_p (mpc_realref (op)) || mpfr_inf_p (mpc_imagref (op)))
{
mpfr_set_inf (mpc_imagref (rop), mpfr_signbit (mpc_imagref (op)) ? +1 : -1);
mpfr_set_nan (mpc_realref (rop));
}
else if (mpfr_zero_p (mpc_realref (op)))
{
inex_re = set_pi_over_2 (mpc_realref (rop), +1, MPC_RND_RE (rnd));
mpfr_set_nan (mpc_imagref (rop));
}
else
{
mpfr_set_nan (mpc_realref (rop));
mpfr_set_nan (mpc_imagref (rop));
}
return MPC_INEX (inex_re, 0);
}
if (mpfr_inf_p (mpc_realref (op)) || mpfr_inf_p (mpc_imagref (op)))
{
if (mpfr_inf_p (mpc_realref (op)))
{
if (mpfr_inf_p (mpc_imagref (op)))
{
if (mpfr_sgn (mpc_realref (op)) > 0)
{
inex_re =
set_pi_over_2 (mpc_realref (rop), +1, MPC_RND_RE (rnd));
mpfr_div_2ui (mpc_realref (rop), mpc_realref (rop), 1, GMP_RNDN);
}
else
{
/* the real part of the result is 3*pi/4
a = o(pi) error(a) < 1 ulp(a)
b = o(3*a) error(b) < 2 ulp(b)
c = b/4 exact
thus 1 bit is lost */
mpfr_t x;
mpfr_prec_t prec;
int ok;
mpfr_init (x);
prec = mpfr_get_prec (mpc_realref (rop));
p = prec;
do
{
p += mpc_ceil_log2 (p);
mpfr_set_prec (x, p);
mpfr_const_pi (x, GMP_RNDD);
mpfr_mul_ui (x, x, 3, GMP_RNDD);
ok =
mpfr_can_round (x, p - 1, GMP_RNDD, MPC_RND_RE (rnd),
prec+(MPC_RND_RE (rnd) == GMP_RNDN));
} while (ok == 0);
inex_re =
mpfr_div_2ui (mpc_realref (rop), x, 2, MPC_RND_RE (rnd));
mpfr_clear (x);
}
}
else
{
if (mpfr_sgn (mpc_realref (op)) > 0)
mpfr_set_ui (mpc_realref (rop), 0, GMP_RNDN);
else
inex_re = mpfr_const_pi (mpc_realref (rop), MPC_RND_RE (rnd));
}
}
else
inex_re = set_pi_over_2 (mpc_realref (rop), +1, MPC_RND_RE (rnd));
mpfr_set_inf (mpc_imagref (rop), mpfr_signbit (mpc_imagref (op)) ? +1 : -1);
return MPC_INEX (inex_re, 0);
}
/* pure real argument */
if (mpfr_zero_p (mpc_imagref (op)))
{
int s_im;
s_im = mpfr_signbit (mpc_imagref (op));
if (mpfr_cmp_ui (mpc_realref (op), 1) > 0)
{
if (s_im)
inex_im = mpfr_acosh (mpc_imagref (rop), mpc_realref (op),
MPC_RND_IM (rnd));
else
inex_im = -mpfr_acosh (mpc_imagref (rop), mpc_realref (op),
INV_RND (MPC_RND_IM (rnd)));
mpfr_set_ui (mpc_realref (rop), 0, GMP_RNDN);
}
else if (mpfr_cmp_si (mpc_realref (op), -1) < 0)
{
mpfr_t minus_op_re;
minus_op_re[0] = mpc_realref (op)[0];
MPFR_CHANGE_SIGN (minus_op_re);
if (s_im)
inex_im = mpfr_acosh (mpc_imagref (rop), minus_op_re,
MPC_RND_IM (rnd));
else
inex_im = -mpfr_acosh (mpc_imagref (rop), minus_op_re,
INV_RND (MPC_RND_IM (rnd)));
inex_re = mpfr_const_pi (mpc_realref (rop), MPC_RND_RE (rnd));
}
else
{
inex_re = mpfr_acos (mpc_realref (rop), mpc_realref (op), MPC_RND_RE (rnd));
mpfr_set_ui (mpc_imagref (rop), 0, MPC_RND_IM (rnd));
}
if (!s_im)
mpc_conj (rop, rop, MPC_RNDNN);
return MPC_INEX (inex_re, inex_im);
}
/* pure imaginary argument */
if (mpfr_zero_p (mpc_realref (op)))
{
inex_re = set_pi_over_2 (mpc_realref (rop), +1, MPC_RND_RE (rnd));
inex_im = -mpfr_asinh (mpc_imagref (rop), mpc_imagref (op),
INV_RND (MPC_RND_IM (rnd)));
mpc_conj (rop,rop, MPC_RNDNN);
return MPC_INEX (inex_re, inex_im);
}
/* regular complex argument: acos(z) = Pi/2 - asin(z) */
p_re = mpfr_get_prec (mpc_realref(rop));
p_im = mpfr_get_prec (mpc_imagref(rop));
p = p_re;
mpc_init3 (z1, p, p_im); /* we round directly the imaginary part to p_im,
with rounding mode opposite to rnd_im */
rnd_im = MPC_RND_IM(rnd);
/* the imaginary part of asin(z) has the same sign as Im(z), thus if
Im(z) > 0 and rnd_im = RNDZ, we want to round the Im(asin(z)) to -Inf
so that -Im(asin(z)) is rounded to zero */
if (rnd_im == GMP_RNDZ)
rnd_im = mpfr_sgn (mpc_imagref(op)) > 0 ? GMP_RNDD : GMP_RNDU;
else
rnd_im = rnd_im == GMP_RNDU ? GMP_RNDD
: rnd_im == GMP_RNDD ? GMP_RNDU
: rnd_im; /* both RNDZ and RNDA map to themselves for -asin(z) */
rnd1 = MPC_RND (GMP_RNDN, rnd_im);
mpfr_init2 (pi_over_2, p);
for (;;)
{
p += mpc_ceil_log2 (p) + 3;
mpfr_set_prec (mpc_realref(z1), p);
mpfr_set_prec (pi_over_2, p);
set_pi_over_2 (pi_over_2, +1, GMP_RNDN);
e1 = 1; /* Exp(pi_over_2) */
inex = mpc_asin (z1, op, rnd1); /* asin(z) */
MPC_ASSERT (mpfr_sgn (mpc_imagref(z1)) * mpfr_sgn (mpc_imagref(op)) > 0);
inex_im = MPC_INEX_IM(inex); /* inex_im is in {-1, 0, 1} */
e2 = mpfr_get_exp (mpc_realref(z1));
mpfr_sub (mpc_realref(z1), pi_over_2, mpc_realref(z1), GMP_RNDN);
if (!mpfr_zero_p (mpc_realref(z1)))
{
/* the error on x=Re(z1) is bounded by 1/2 ulp(x) + 2^(e1-p-1) +
2^(e2-p-1) */
e1 = e1 >= e2 ? e1 + 1 : e2 + 1;
/* the error on x is bounded by 1/2 ulp(x) + 2^(e1-p-1) */
e1 -= mpfr_get_exp (mpc_realref(z1));
/* the error on x is bounded by 1/2 ulp(x) [1 + 2^e1] */
e1 = e1 <= 0 ? 0 : e1;
/* the error on x is bounded by 2^e1 * ulp(x) */
mpfr_neg (mpc_imagref(z1), mpc_imagref(z1), GMP_RNDN); /* exact */
inex_im = -inex_im;
if (mpfr_can_round (mpc_realref(z1), p - e1, GMP_RNDN, GMP_RNDZ,
p_re + (MPC_RND_RE(rnd) == GMP_RNDN)))
break;
}
}
inex = mpc_set (rop, z1, rnd);
inex_re = MPC_INEX_RE(inex);
mpc_clear (z1);
mpfr_clear (pi_over_2);
return MPC_INEX(inex_re, inex_im);
}
mpcomplex mpcomplex::conj2() {
mpc_conj(mpc_val, mpc_val, default_rnd);
return *this;
}