LOG(3)

NAME
1.33 `log', `logf'--natural logarithms

SYNOPSIS
     #include <math.h>
     double log(double X);
     float logf(float X);

DESCRIPTION
Return the natural logarithm of X, that is, its logarithm base e (where e is the base of the natural system of logarithms, 2.71828...). `log' and `logf' are identical save for the return and argument types.
   You can use the (non-ANSI) function `matherr' to specify error handling for these functions.

RETURNS
Normally, returns the calculated value. When X is zero, the returned value is `-HUGE_VAL' and `errno' is set to `ERANGE'. When X is negative, the returned value is NaN (not a number) and `errno' is set to `EDOM'. You can control the error behavior via `matherr'.

PORTABILITY
`log' is ANSI. `logf' is an extension.

SEE ALSO
log is part of the library. The full documentation for is maintained as a Texinfo manual. If info and are properly installed at your site, the command

    info

will give you access to the complete manual.