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).

       allbox;  lbw24  lb  lb  l  l  l.   Interface Attribute Value T{ clog(),
       clogf(), clogl() T}   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)