CLOG(3)			   Linux Programmer's Manual		       CLOG(3)



NAME
       clog, clogf, clogl - natural logarithm of a complex number

SYNOPSIS
       #include <complex.h>

       double complex clog(double complex z);
       float complex clogf(float complex z);
       long double complex clogl(long double complex z);

       Link with -lm.

DESCRIPTION
       These  functions	 calculate  the complex natural logarithm of z, with a
       branch cut along the negative real axis.

       The logarithm  clog()  is  the  inverse	function  of  the  exponential
       cexp(3).	  Thus,	 if y = clog(z), then z = cexp(y).  The imaginary part
       of y is chosen in the interval [-pi,pi].

       One has:

	   clog(z) = log(cabs(z)) + I * carg(z)

       Note that z close to zero will cause an overflow.

VERSIONS
       These functions first appeared in glibc in version 2.1.

ATTRIBUTES
       For  an	explanation  of	 the  terms  used   in	 this	section,   see
       attributes(7).

       +-------------------------+---------------+---------+
       |Interface		 | Attribute	 | Value   |
       +-------------------------+---------------+---------+
       |clog(), clogf(), clogl() | Thread safety | MT-Safe |
       +-------------------------+---------------+---------+
CONFORMING TO
       C99, POSIX.1-2001, POSIX.1-2008.

SEE ALSO
       cabs(3), cexp(3), clog10(3), clog2(3), complex(7)

COLOPHON
       This  page  is  part of release 4.10 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest	  version     of     this    page,    can    be	   found    at
       https://www.kernel.org/doc/man-pages/.



				  2015-04-19			       CLOG(3)