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

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   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/.

                              2015-04-19                           CLOG(3)

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