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path: root/src/math/coshf.c
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 ```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 ``` ``````/* origin: FreeBSD /usr/src/lib/msun/src/e_coshf.c */ /* * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunPro, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== */ #include "libm.h" float coshf(float x) { union {float f; uint32_t i;} u = {.f = x}; uint32_t ix; float t; /* |x| */ u.i &= 0x7fffffff; x = u.f; ix = u.i; /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */ if (ix < 0x3eb17218) { t = expm1f(x); if (ix < 0x39800000) return 1; return 1 + t*t/(2*(1+t)); } /* |x| in [0.5*ln2,9], return (exp(|x|)+1/exp(|x|))/2; */ if (ix < 0x41100000) { t = expf(x); return 0.5f*t + 0.5f/t; } /* |x| in [9, log(maxfloat)] return 0.5f*exp(|x|) */ if (ix < 0x42b17217) return 0.5f*expf(x); /* |x| in [log(maxfloat), overflowthresold] */ if (ix <= 0x42b2d4fc) return __expo2f(x); /* |x| > overflowthresold or nan */ x *= 0x1p127f; return x; } ``````