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).

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)