text: 
  /* @(#)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) */
  