NAME

       clog, clogf, clogl - natural logarithm of a complex number

LIBRARY

       Math library (libm, -lm)

SYNOPSIS

       #include <complex.h>

       double complex clog(double complex z);
       float complex clogf(float complex z);
       long double complex clogl(long double complex z);

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.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                      │ Attribute     │ Value   │
       ├───────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │clog(), clogf(), clogl()                                       │ Thread safety │ MT-Safe │
       └───────────────────────────────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       C11, POSIX.1-2008.

HISTORY

       glibc 2.1.  C99, POSIX.1-2001.

SEE ALSO

       cabs(3), cexp(3), clog10(3), clog2(3), complex(7)