+/* 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 "libm.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 cpack(cosh(x), x * y);
+ if (ix < 0x40360000) /* small x: normal case */
+ return cpack(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 cpack(h * cos(y), copysign(h, x) * sin(y));
+ } else if (ix < 0x4096bbaa) {
+ /* x < 1455: scale to avoid overflow */
+ z = __ldexp_cexp(cpack(fabs(x), y), -1);
+ return cpack(creal(z), cimag(z) * copysign(1, x));
+ } else {
+ /* x >= 1455: the result always overflows */
+ h = huge * x;
+ return cpack(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 cpack(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 cpack(x * x, copysign(0, x) * y);
+ return cpack(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 cpack(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 cpack(x * x, x * (y - y));
+ return cpack((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 cpack((x * x) * (y - y), (x + x) * (y - y));
+}
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