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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 4.15 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)