/* origin: FreeBSD /usr/src/lib/msun/src/s_ccosh.c */
/*-
* Copyright (c) 2005 Bruce D. Evans and Steven G. Kargl
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice unmodified, this list of conditions, and the following
* disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Hyperbolic cosine of a complex argument z = x + i y.
*
* cosh(z) = cosh(x+iy)
* = cosh(x) cos(y) + i sinh(x) sin(y).
*
* Exceptional values are noted in the comments within the source code.
* These values and the return value were taken from n1124.pdf.
*/
#include "complex_impl.h"
static const double huge = 0x1p1023;
double complex ccosh(double complex z)
{
double x, y, h;
int32_t hx, hy, ix, iy, lx, ly;
x = creal(z);
y = cimag(z);
EXTRACT_WORDS(hx, lx, x);
EXTRACT_WORDS(hy, ly, y);
ix = 0x7fffffff & hx;
iy = 0x7fffffff & hy;
/* Handle the nearly-non-exceptional cases where x and y are finite. */
if (ix < 0x7ff00000 && iy < 0x7ff00000) {
if ((iy | ly) == 0)
return CMPLX(cosh(x), x * y);
if (ix < 0x40360000) /* small x: normal case */
return CMPLX(cosh(x) * cos(y), sinh(x) * sin(y));
/* |x| >= 22, so cosh(x) ~= exp(|x|) */
if (ix < 0x40862e42) {
/* x < 710: exp(|x|) won't overflow */
h = exp(fabs(x)) * 0.5;
return CMPLX(h * cos(y), copysign(h, x) * sin(y));
} else if (ix < 0x4096bbaa) {
/* x < 1455: scale to avoid overflow */
z = __ldexp_cexp(CMPLX(fabs(x), y), -1);
return CMPLX(creal(z), cimag(z) * copysign(1, x));
} else {
/* x >= 1455: the result always overflows */
h = huge * x;
return CMPLX(h * h * cos(y), h * sin(y));
}
}
/*
* cosh(+-0 +- I Inf) = dNaN + I sign(d(+-0, dNaN))0.
* The sign of 0 in the result is unspecified. Choice = normally
* the same as dNaN. Raise the invalid floating-point exception.
*
* cosh(+-0 +- I NaN) = d(NaN) + I sign(d(+-0, NaN))0.
* The sign of 0 in the result is unspecified. Choice = normally
* the same as d(NaN).
*/
if ((ix | lx) == 0 && iy >= 0x7ff00000)
return CMPLX(y - y, copysign(0, x * (y - y)));
/*
* cosh(+-Inf +- I 0) = +Inf + I (+-)(+-)0.
*
* cosh(NaN +- I 0) = d(NaN) + I sign(d(NaN, +-0))0.
* The sign of 0 in the result is unspecified.
*/
if ((iy | ly) == 0 && ix >= 0x7ff00000) {
if (((hx & 0xfffff) | lx) == 0)
return CMPLX(x * x, copysign(0, x) * y);
return CMPLX(x * x, copysign(0, (x + x) * y));
}
/*
* cosh(x +- I Inf) = dNaN + I dNaN.
* Raise the invalid floating-point exception for finite nonzero x.
*
* cosh(x + I NaN) = d(NaN) + I d(NaN).
* Optionally raises the invalid floating-point exception for finite
* nonzero x. Choice = don't raise (except for signaling NaNs).
*/
if (ix < 0x7ff00000 && iy >= 0x7ff00000)
return CMPLX(y - y, x * (y - y));
/*
* cosh(+-Inf + I NaN) = +Inf + I d(NaN).
*
* cosh(+-Inf +- I Inf) = +Inf + I dNaN.
* The sign of Inf in the result is unspecified. Choice = always +.
* Raise the invalid floating-point exception.
*
* cosh(+-Inf + I y) = +Inf cos(y) +- I Inf sin(y)
*/
if (ix >= 0x7ff00000 && ((hx & 0xfffff) | lx) == 0) {
if (iy >= 0x7ff00000)
return CMPLX(x * x, x * (y - y));
return CMPLX((x * x) * cos(y), x * sin(y));
}
/*
* cosh(NaN + I NaN) = d(NaN) + I d(NaN).
*
* cosh(NaN +- I Inf) = d(NaN) + I d(NaN).
* Optionally raises the invalid floating-point exception.
* Choice = raise.
*
* cosh(NaN + I y) = d(NaN) + I d(NaN).
* Optionally raises the invalid floating-point exception for finite
* nonzero y. Choice = don't raise (except for signaling NaNs).
*/
return CMPLX((x * x) * (y - y), (x + x) * (y - y));
}
