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 4.04 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 http://www.kernel.org/doc/man-pages/.

                                            2015-04-19                                    CLOG(3)