| |
| /* @(#)w_log10.c 5.1 93/09/24 */ |
| /* |
| * ==================================================== |
| * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| * |
| * Developed at SunPro, a Sun Microsystems, Inc. business. |
| * Permission to use, copy, modify, and distribute this |
| * software is freely granted, provided that this notice |
| * is preserved. |
| * ==================================================== |
| */ |
| |
| /* |
| FUNCTION |
| <<log10>>, <<log10f>>---base 10 logarithms |
| |
| INDEX |
| log10 |
| INDEX |
| log10f |
| |
| ANSI_SYNOPSIS |
| #include <math.h> |
| double log10(double <[x]>); |
| float log10f(float <[x]>); |
| |
| TRAD_SYNOPSIS |
| #include <math.h> |
| double log10(<[x]>) |
| double <[x]>; |
| |
| float log10f(<[x]>) |
| float <[x]>; |
| |
| DESCRIPTION |
| <<log10>> returns the base 10 logarithm of <[x]>. |
| It is implemented as <<log(<[x]>) / log(10)>>. |
| |
| <<log10f>> is identical, save that it takes and returns <<float>> values. |
| |
| RETURNS |
| <<log10>> and <<log10f>> return the calculated value. |
| |
| See the description of <<log>> for information on errors. |
| |
| PORTABILITY |
| <<log10>> is ANSI C. <<log10f>> is an extension. |
| |
| */ |
| |
| /* |
| * wrapper log10(X) |
| */ |
| |
| #include "fdlibm.h" |
| #include <errno.h> |
| |
| #ifndef _DOUBLE_IS_32BITS |
| |
| #ifdef __STDC__ |
| double log10(double x) /* wrapper log10 */ |
| #else |
| double log10(x) /* wrapper log10 */ |
| double x; |
| #endif |
| { |
| #ifdef _IEEE_LIBM |
| return __ieee754_log10(x); |
| #else |
| double z; |
| struct exception exc; |
| z = __ieee754_log10(x); |
| if(_LIB_VERSION == _IEEE_ || isnan(x)) return z; |
| if(x<=0.0) { |
| #ifndef HUGE_VAL |
| #define HUGE_VAL inf |
| double inf = 0.0; |
| |
| SET_HIGH_WORD(inf,0x7ff00000); /* set inf to infinite */ |
| #endif |
| exc.name = "log10"; |
| exc.err = 0; |
| exc.arg1 = x; |
| exc.arg2 = x; |
| if (_LIB_VERSION == _SVID_) |
| exc.retval = -HUGE; |
| else |
| exc.retval = -HUGE_VAL; |
| if(x==0.0) { |
| /* log10(0) */ |
| exc.type = SING; |
| if (_LIB_VERSION == _POSIX_) |
| errno = ERANGE; |
| else if (!matherr(&exc)) { |
| errno = ERANGE; |
| } |
| } else { |
| /* log10(x<0) */ |
| exc.type = DOMAIN; |
| if (_LIB_VERSION == _POSIX_) |
| errno = EDOM; |
| else if (!matherr(&exc)) { |
| errno = EDOM; |
| } |
| exc.retval = nan(""); |
| } |
| if (exc.err != 0) |
| errno = exc.err; |
| return exc.retval; |
| } else |
| return z; |
| #endif |
| } |
| |
| #endif /* defined(_DOUBLE_IS_32BITS) */ |