logl


SYNOPSIS
       #include <math.h>

       double log(double x);
       float logf(float x);
       long double logl(long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       logf(), logl():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 ||
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99

DESCRIPTION
       The log() function returns the natural logarithm of x.

RETURN VALUE
       On success, these functions return the natural logarithm of x.

       If x is a NaN, a NaN is returned.

       If x is 1, the result is +0.

       If x is positive infinity, positive infinity is returned.

       If x is zero, then a  pole  error  occurs,  and  the  functions  return
       -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, respectively.

       If  x  is  negative  (including negative infinity), then a domain error
       occurs, and a NaN (not a number) is returned.

ERRORS
       See math_error(7) for information on how to determine whether an  error
       has occurred when calling these functions.

       The following errors can occur:

       Domain error: x is negative
              errno  is  set  to  EDOM.   An  invalid floating-point exception
              (FE_INVALID) is raised.

       Pole error: x is zero
              errno is set to ERANGE.  A divide-by-zero floating-point  excep-
              tion (FE_DIVBYZERO) is raised.

CONFORMING TO
       C99, POSIX.1-2001.  The variant returning double also conforms to SVr4,
       4.3BSD, C89.

BUGS

                                  2010-09-20                            LOG(3)
Man Pages Copyright Respective Owners. Site Copyright (C) 1994 - 2017 Hurricane Electric. All Rights Reserved.