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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 | ANSI_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 | TRAD_SYNOPSIS
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| 29 | #include <math.h>
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| 30 | double acos(<[x]>)
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| 31 | double <[x]>;
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| 32 |
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| 33 | float acosf(<[x]>)
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| 34 | float <[x]>;
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| 35 |
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| 36 |
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| 37 |
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| 38 | DESCRIPTION
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| 39 |
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| 40 | <<acos>> computes the inverse cosine (arc cosine) of the input value.
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| 41 | Arguments to <<acos>> must be in the range @minus{}1 to 1.
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| 42 |
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| 43 | <<acosf>> is identical to <<acos>>, except that it performs
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| 44 | its calculations on <<floats>>.
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| 45 |
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| 46 | RETURNS
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| 47 | @ifinfo
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| 48 | <<acos>> and <<acosf>> return values in radians, in the range of 0 to pi.
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| 49 | @end ifinfo
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| 50 | @tex
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| 51 | <<acos>> and <<acosf>> return values in radians, in the range of <<0>> to $\pi$.
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| 52 | @end tex
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| 53 |
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| 54 | If <[x]> is not between @minus{}1 and 1, the returned value is NaN
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| 55 | (not a number) the global variable <<errno>> is set to <<EDOM>>, and a
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| 56 | <<DOMAIN error>> message is sent as standard error output.
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| 57 |
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| 58 | You can modify error handling for these functions using <<matherr>>.
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| 59 |
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| 60 |
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| 61 | QUICKREF ANSI SVID POSIX RENTRANT
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| 62 | acos y,y,y,m
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| 63 | acosf n,n,n,m
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| 64 |
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| 65 | MATHREF
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| 66 | acos, [-1,1], acos(arg),,,
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| 67 | acos, NAN, arg,DOMAIN,EDOM
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| 68 |
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| 69 | MATHREF
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| 70 | acosf, [-1,1], acosf(arg),,,
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| 71 | acosf, NAN, argf,DOMAIN,EDOM
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| 72 |
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| 73 | */
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| 74 |
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| 75 | /*
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| 76 | * wrap_acos(x)
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| 77 | */
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| 78 |
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| 79 | #include "fdlibm.h"
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| 80 | #include <errno.h>
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| 81 |
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| 82 | #ifndef _DOUBLE_IS_32BITS
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| 83 |
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| 84 | #ifdef __STDC__
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| 85 | double acos(double x) /* wrapper acos */
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| 86 | #else
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| 87 | double acos(x) /* wrapper acos */
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| 88 | double x;
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| 89 | #endif
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| 90 | {
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| 91 | #ifdef _IEEE_LIBM
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| 92 | return __ieee754_acos(x);
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| 93 | #else
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| 94 | double z;
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| 95 | struct exception exc;
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| 96 | z = __ieee754_acos(x);
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| 97 | if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
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| 98 | if(fabs(x)>1.0) {
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| 99 | /* acos(|x|>1) */
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| 100 | exc.type = DOMAIN;
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| 101 | exc.name = "acos";
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| 102 | exc.err = 0;
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| 103 | exc.arg1 = exc.arg2 = x;
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| 104 | exc.retval = 0.0;
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| 105 | if (_LIB_VERSION == _POSIX_)
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| 106 | errno = EDOM;
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| 107 | else if (!matherr(&exc)) {
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| 108 | errno = EDOM;
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| 109 | }
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| 110 | if (exc.err != 0)
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| 111 | errno = exc.err;
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| 112 | return exc.retval;
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| 113 | } else
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| 114 | return z;
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| 115 | #endif
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| 116 | }
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| 117 |
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| 118 | #endif /* defined(_DOUBLE_IS_32BITS) */
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