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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 4.16 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)