LOG(3) NEWLIB 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 han‐
dling 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 nega‐
tive, 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 ALSOlog 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.
NEWLIB April 2010 LOG(3)
