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| 2 | /* @(#)w_acos.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 | FUNCTION |
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| 16 | <<acos>>, <<acosf>>---arc cosine |
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| 17 | |
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| 18 | INDEX |
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| 19 | acos |
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| 20 | INDEX |
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| 21 | acosf |
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| 22 | |
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| 23 | SYNOPSIS |
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| 24 | #include <math.h> |
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| 25 | double acos(double <[x]>); |
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| 26 | float acosf(float <[x]>); |
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| 27 | |
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| 28 | DESCRIPTION |
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| 29 | |
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| 30 | <<acos>> computes the inverse cosine (arc cosine) of the input value. |
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| 31 | Arguments to <<acos>> must be in the range @minus{}1 to 1. |
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| 32 | |
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| 33 | <<acosf>> is identical to <<acos>>, except that it performs |
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| 34 | its calculations on <<floats>>. |
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| 35 | |
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| 36 | RETURNS |
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| 37 | @ifnottex |
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| 38 | <<acos>> and <<acosf>> return values in radians, in the range of 0 to pi. |
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| 39 | @end ifnottex |
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| 40 | @tex |
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| 41 | <<acos>> and <<acosf>> return values in radians, in the range of <<0>> to $\pi$. |
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| 42 | @end tex |
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| 43 | |
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| 44 | If <[x]> is not between @minus{}1 and 1, the returned value is NaN |
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| 45 | (not a number) the global variable <<errno>> is set to <<EDOM>>, and a |
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| 46 | <<DOMAIN error>> message is sent as standard error output. |
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| 47 | |
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| 48 | You can modify error handling for these functions using <<matherr>>. |
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| 49 | |
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| 50 | |
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| 51 | QUICKREF |
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| 52 | ansi svid posix rentrant |
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| 53 | acos y,y,y,m |
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| 54 | acosf n,n,n,m |
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| 55 | |
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| 56 | MATHREF |
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| 57 | acos, [-1,1], acos(arg),,, |
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| 58 | acos, NAN, arg,DOMAIN,EDOM |
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| 59 | |
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| 60 | MATHREF |
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| 61 | acosf, [-1,1], acosf(arg),,, |
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| 62 | acosf, NAN, argf,DOMAIN,EDOM |
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| 63 | |
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| 64 | */ |
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| 65 | |
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| 66 | /* |
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| 67 | * wrap_acos(x) |
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| 68 | */ |
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| 69 | |
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| 70 | #include "fdlibm.h" |
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| 71 | #include <errno.h> |
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| 72 | |
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| 73 | #ifndef _DOUBLE_IS_32BITS |
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| 74 | |
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| 75 | #ifdef __STDC__ |
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| 76 | double acos(double x) /* wrapper acos */ |
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| 77 | #else |
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| 78 | double acos(x) /* wrapper acos */ |
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| 79 | double x; |
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| 80 | #endif |
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| 81 | { |
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| 82 | #ifdef _IEEE_LIBM |
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| 83 | return __ieee754_acos(x); |
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| 84 | #else |
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| 85 | double z; |
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| 86 | struct exception exc; |
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| 87 | z = __ieee754_acos(x); |
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| 88 | if(_LIB_VERSION == _IEEE_ || isnan(x)) return z; |
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| 89 | if(fabs(x)>1.0) { |
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| 90 | /* acos(|x|>1) */ |
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| 91 | exc.type = DOMAIN; |
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| 92 | exc.name = "acos"; |
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| 93 | exc.err = 0; |
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| 94 | exc.arg1 = exc.arg2 = x; |
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| 95 | exc.retval = nan(""); |
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| 96 | if (_LIB_VERSION == _POSIX_) |
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| 97 | errno = EDOM; |
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| 98 | else if (!matherr(&exc)) { |
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| 99 | errno = EDOM; |
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| 100 | } |
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| 101 | if (exc.err != 0) |
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| 102 | errno = exc.err; |
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| 103 | return exc.retval; |
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| 104 | } else |
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| 105 | return z; |
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| 106 | #endif |
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| 107 | } |
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| 108 | |
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| 109 | #endif /* defined(_DOUBLE_IS_32BITS) */ |
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