43 lines
779 B
C
43 lines
779 B
C
/* _Cosh function */
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#include "wctype.h"
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#include "xmath.h"
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_STD_BEGIN
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_CRTIMP2 double __cdecl _Cosh(double x, double y)
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{ /* compute y * cosh(x), |y| <= 1 */
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switch (_Dtest(&x))
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{ /* test for special codes */
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case NAN:
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errno = EDOM;
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return (x);
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case INF:
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if (y == 0)
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return (0);
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errno = ERANGE;
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return (_Inf._D);
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case 0:
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return (y);
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default: /* finite */
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if (x < 0)
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x = -x;
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if (x < _Xbig)
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{ /* worth adding in exp(-x) */
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_Exp(&x, 1, -1);
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return (y * (x + 0.25 / x));
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}
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if (0 <= _Exp(&x, y, -1))
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errno = ERANGE; /* x large */
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return (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) 1994 by P.J. Plauger. ALL RIGHTS RESERVED.
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* Consult your license regarding permissions and restrictions.
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*/
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/*
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941029 pjp: added _STD machinery
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*/
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