newlib/libm/mathfp/s_log10.c

   1
   2 /* @(#)z_log10.c 1.0 98/08/13 */
   3 /******************************************************************
   4  * Logarithm
   5  *
   6  * Input:
   7  *   x - floating point value
   8  *
   9  * Output:
  10  *   logarithm of x
  11  *
  12  * Description:
  13  *   This routine returns the logarithm of x (base 10).
  14  *
  15  *****************************************************************/
  16
  17 /*
  18 FUNCTION
  19         <<log10>>, <<log10f>>---base 10 logarithms
  20
  21 INDEX
  22 log10
  23 INDEX
  24 log10f
  25
  26 SYNOPSIS
  27         #include <math.h>
  28         double log10(double <[x]>);
  29         float log10f(float <[x]>);
  30
  31 DESCRIPTION
  32 <<log10>> returns the base 10 logarithm of <[x]>.
  33 It is implemented as <<log(<[x]>) / log(10)>>.
  34
  35 <<log10f>> is identical, save that it takes and returns <<float>> values.
  36
  37 RETURNS
  38 <<log10>> and <<log10f>> return the calculated value.
  39
  40 See the description of <<log>> for information on errors.
  41
  42 PORTABILITY
  43 <<log10>> is ANSI C.  <<log10f>> is an extension.
  44
  45 */
  46
  47
  48 #include "fdlibm.h"
  49 #include "zmath.h"
  50
  51 #ifndef _DOUBLE_IS_32BITS
  52
  53 double
  54 log10 (double x)
  55 {
  56   return (logarithm (x, 1));
  57 }
  58
  59 #endif /* _DOUBLE_IS_32BITS */