68 lines
1.3 KiB
C
68 lines
1.3 KiB
C
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/* _Sinh function */
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#include "xmath.h"
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_STD_BEGIN
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/* coefficients */
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#define NP (sizeof (p) / sizeof (p[0]) - 1)
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static const double p[] = { /* courtesy Dr. Tim Prince */
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0.0000000001632881,
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0.0000000250483893,
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0.0000027557344615,
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0.0001984126975233,
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0.0083333333334816,
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0.1666666666666574,
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1.0000000000000001};
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_CRTIMP2 double __cdecl _Sinh(double x, double y)
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{ /* compute y*sinh(x), |y| <= 1 */
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short neg;
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switch (_Dtest(&x))
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{ /* test for special codes */
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case _NANCODE:
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return (x);
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case _INFCODE:
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return (y != 0.0 ? x : DSIGN(x) ? -y : y);
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case 0:
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return (x * y);
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default: /* finite */
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if (y == 0.0)
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return (x < 0.0 ? -y : y);
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if (x < 0.0)
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x = -x, neg = 1;
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else
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neg = 0;
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if (x < _Rteps._Double)
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x *= y; /* x tiny */
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else if (x < 1.0)
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{
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double w = x * x;
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x += x * w * _Poly(w, p, NP - 1);
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x *= y;
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}
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else if (x < _Xbig)
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{ /* worth adding in exp(-x) */
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_Exp(&x, 1.0, -1);
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x = y * (x - 0.25 / x);
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}
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else
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switch (_Exp(&x, y, -1))
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{ /* report over/underflow */
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case 0:
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_Feraise(_FE_UNDERFLOW);
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break;
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case _INFCODE:
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_Feraise(_FE_OVERFLOW);
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}
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return (neg ? -x : x);
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}
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}
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_STD_END
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/*
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* Copyright (c) 1992-2001 by P.J. Plauger. ALL RIGHTS RESERVED.
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* Consult your license regarding permissions and restrictions.
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V3.10:0009 */
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