| 1 | |
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| 2 | /* @(#)w_cosh.c 5.1 93/09/24 */ |
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| 3 | /* |
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| 4 | * ==================================================== |
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| 5 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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| 6 | * |
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| 7 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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| 8 | * Permission to use, copy, modify, and distribute this |
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| 9 | * software is freely granted, provided that this notice |
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| 10 | * is preserved. |
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| 11 | * ==================================================== |
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| 12 | */ |
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| 13 | |
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| 14 | /* |
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| 15 | |
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| 16 | FUNCTION |
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| 17 | <<cosh>>, <<coshf>>---hyperbolic cosine |
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| 18 | |
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| 19 | SYNOPSIS |
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| 20 | #include <math.h> |
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| 21 | double cosh(double <[x]>); |
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| 22 | float coshf(float <[x]>); |
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| 23 | |
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| 24 | DESCRIPTION |
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| 25 | |
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| 26 | <<cosh>> computes the hyperbolic cosine of the argument <[x]>. |
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| 27 | <<cosh(<[x]>)>> is defined as |
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| 28 | @ifnottex |
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| 29 | . (exp(x) + exp(-x))/2 |
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| 30 | @end ifnottex |
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| 31 | @tex |
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| 32 | $${(e^x + e^{-x})} \over 2$$ |
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| 33 | @end tex |
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| 34 | |
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| 35 | Angles are specified in radians. |
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| 36 | |
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| 37 | <<coshf>> is identical, save that it takes and returns <<float>>. |
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| 38 | |
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| 39 | RETURNS |
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| 40 | The computed value is returned. When the correct value would create |
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| 41 | an overflow, <<cosh>> returns the value <<HUGE_VAL>> with the |
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| 42 | appropriate sign, and the global value <<errno>> is set to <<ERANGE>>. |
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| 43 | |
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| 44 | You can modify error handling for these functions using the |
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| 45 | function <<matherr>>. |
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| 46 | |
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| 47 | PORTABILITY |
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| 48 | <<cosh>> is ANSI. |
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| 49 | <<coshf>> is an extension. |
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| 50 | |
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| 51 | QUICKREF |
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| 52 | cosh ansi pure |
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| 53 | coshf - pure |
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| 54 | */ |
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| 55 | |
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| 56 | /* |
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| 57 | * wrapper cosh(x) |
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| 58 | */ |
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| 59 | |
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| 60 | #include "fdlibm.h" |
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| 61 | #include <errno.h> |
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| 62 | |
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| 63 | #ifndef _DOUBLE_IS_32BITS |
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| 64 | |
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| 65 | #ifdef __STDC__ |
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| 66 | double cosh(double x) /* wrapper cosh */ |
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| 67 | #else |
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| 68 | double cosh(x) /* wrapper cosh */ |
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| 69 | double x; |
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| 70 | #endif |
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| 71 | { |
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| 72 | #ifdef _IEEE_LIBM |
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| 73 | return __ieee754_cosh(x); |
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| 74 | #else |
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| 75 | double z; |
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| 76 | struct exception exc; |
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| 77 | z = __ieee754_cosh(x); |
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| 78 | if(_LIB_VERSION == _IEEE_ || isnan(x)) return z; |
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| 79 | if(fabs(x)>7.10475860073943863426e+02) { |
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| 80 | /* cosh(finite) overflow */ |
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| 81 | #ifndef HUGE_VAL |
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| 82 | #define HUGE_VAL inf |
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| 83 | double inf = 0.0; |
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| 84 | |
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| 85 | SET_HIGH_WORD(inf,0x7ff00000); /* set inf to infinite */ |
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| 86 | #endif |
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| 87 | exc.type = OVERFLOW; |
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| 88 | exc.name = "cosh"; |
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| 89 | exc.err = 0; |
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| 90 | exc.arg1 = exc.arg2 = x; |
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| 91 | if (_LIB_VERSION == _SVID_) |
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| 92 | exc.retval = HUGE; |
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| 93 | else |
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| 94 | exc.retval = HUGE_VAL; |
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| 95 | if (_LIB_VERSION == _POSIX_) |
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| 96 | errno = ERANGE; |
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| 97 | else if (!matherr(&exc)) { |
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| 98 | errno = ERANGE; |
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| 99 | } |
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| 100 | if (exc.err != 0) |
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| 101 | errno = exc.err; |
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| 102 | return exc.retval; |
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| 103 | } else |
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| 104 | return z; |
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| 105 | #endif |
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| 106 | } |
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| 107 | |
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| 108 | #endif /* defined(_DOUBLE_IS_32BITS) */ |
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