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clog

Section: C Library Functions (3)
Updated: 202-0-08
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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	M-Safe

STANDARDS

C11, POSIX.-2008.

HISTORY

glibc 2.1. C99, POSIX.-2001.