| 1 | |
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| 2 | /* @(#)w_log10.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 | <<log10>>, <<log10f>>---base 10 logarithms |
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| 17 | |
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| 18 | INDEX |
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| 19 | log10 |
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| 20 | INDEX |
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| 21 | log10f |
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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 log10(double <[x]>); |
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| 26 | float log10f(float <[x]>); |
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| 27 | |
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| 28 | DESCRIPTION |
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| 29 | <<log10>> returns the base 10 logarithm of <[x]>. |
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| 30 | It is implemented as <<log(<[x]>) / log(10)>>. |
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| 31 | |
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| 32 | <<log10f>> is identical, save that it takes and returns <<float>> values. |
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| 33 | |
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| 34 | RETURNS |
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| 35 | <<log10>> and <<log10f>> return the calculated value. |
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| 36 | |
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| 37 | See the description of <<log>> for information on errors. |
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| 38 | |
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| 39 | PORTABILITY |
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| 40 | <<log10>> is ANSI C. <<log10f>> is an extension. |
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| 41 | |
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| 42 | */ |
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| 43 | |
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| 44 | /* |
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| 45 | * wrapper log10(X) |
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| 46 | */ |
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| 47 | |
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| 48 | #include "fdlibm.h" |
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| 49 | #include <errno.h> |
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| 50 | |
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| 51 | #ifndef _DOUBLE_IS_32BITS |
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| 52 | |
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| 53 | #ifdef __STDC__ |
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| 54 | double log10(double x) /* wrapper log10 */ |
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| 55 | #else |
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| 56 | double log10(x) /* wrapper log10 */ |
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| 57 | double x; |
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| 58 | #endif |
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| 59 | { |
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| 60 | #ifdef _IEEE_LIBM |
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| 61 | return __ieee754_log10(x); |
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| 62 | #else |
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| 63 | double z; |
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| 64 | struct exception exc; |
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| 65 | z = __ieee754_log10(x); |
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| 66 | if(_LIB_VERSION == _IEEE_ || isnan(x)) return z; |
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| 67 | if(x<=0.0) { |
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| 68 | #ifndef HUGE_VAL |
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| 69 | #define HUGE_VAL inf |
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| 70 | double inf = 0.0; |
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| 71 | |
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| 72 | SET_HIGH_WORD(inf,0x7ff00000); /* set inf to infinite */ |
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| 73 | #endif |
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| 74 | exc.name = "log10"; |
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| 75 | exc.err = 0; |
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| 76 | exc.arg1 = x; |
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| 77 | exc.arg2 = x; |
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| 78 | if (_LIB_VERSION == _SVID_) |
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| 79 | exc.retval = -HUGE; |
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| 80 | else |
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| 81 | exc.retval = -HUGE_VAL; |
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| 82 | if(x==0.0) { |
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| 83 | /* log10(0) */ |
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| 84 | exc.type = SING; |
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| 85 | if (_LIB_VERSION == _POSIX_) |
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| 86 | errno = ERANGE; |
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| 87 | else if (!matherr(&exc)) { |
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| 88 | errno = ERANGE; |
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| 89 | } |
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| 90 | } else { |
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| 91 | /* log10(x<0) */ |
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| 92 | exc.type = DOMAIN; |
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| 93 | if (_LIB_VERSION == _POSIX_) |
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| 94 | errno = EDOM; |
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| 95 | else if (!matherr(&exc)) { |
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| 96 | errno = EDOM; |
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| 97 | } |
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| 98 | exc.retval = nan(""); |
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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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