log10(3M)

NAME

     log10 - base 10 logarithm function

SYNOPSIS

     cc [ flag ... ] file ... -lm [ library ... ]
     #include <math.h>

     double log10(double x);

DESCRIPTION

     The log10() function computes the base 10  logarithm  of  x,
     log10(x). The value of x must be positive.

RETURN VALUES

     Upon successful completion, log10() returns the base 10 log-
     arithm of x.

     If x is NaN, NaN is returned. If x is less than 0, -HUGE_VAL
     or  NaN  is  returned,  and errno is set to EDOM. If x is 0,
     -HUGE_VAL is returned and errno may be set to ERANGE.

     For exceptional cases, matherr(3M) tabulates the  values  to
     be returned as dictated by Standards other than XPG4.

ERRORS

     The log10() function will fail if:

     EDOM  The value of x is negative.

     The log10() function may fail if:

     ERANGE
           The value of x is 0.

     No other errors will occur.

USAGE

     An application wishing to check for error situations  should
     set  errno to 0 before calling log10(). If errno is non-zero
     on return,  or  the  return  value  is  NaN,  an  error  has
     occurred.

ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|

SEE ALSO

     isnan(3M),  log(3M),  matherr(3M),  pow(3M),  attributes(5),
     standards(5)