lib/math/log10.c

   1 /*
   2  * (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
   3  * See the copyright notice in the ACK home directory, in the file "Copyright".
   4  *
   5  * Author: Ceriel J.H. Jacobs
   6  */
   7 /* $Header$ */
   8
   9 #include        <math.h>
  10 #include        <errno.h>
  11 #include        "localmath.h"
  12
  13 double
  14 log10(double x)
  15 {
  16         if (__IsNan(x)) {
  17                 errno = EDOM;
  18                 return x;
  19         }
  20         if (x < 0) {
  21                 errno = EDOM;
  22                 return -HUGE_VAL;
  23         }
  24         else if (x == 0) {
  25                 errno = ERANGE;
  26                 return -HUGE_VAL;
  27         }
  28
  29         return log(x) / M_LN10;
  30 }