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 4.16 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/.



                                  2017-09-15                           CLOG(3)