clog man page


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

clog, clogf, clogl — complex natural logarithm functions


#include <complex.h>

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


The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1‐2008 defers to the ISO C standard.

These functions shall compute the complex natural (base e) logarithm of z, with a branch cut along the negative real axis.

Return Value

These functions shall return the complex natural logarithm value, in the range of a strip mathematically unbounded along the real axis and in the interval [-iπ, +iπ] along the imaginary axis.


No errors are defined.

The following sections are informative.

See Also


The Base Definitions volume of POSIX.1‐2008, <complex.h>


2013 IEEE/The Open Group POSIX Programmer's Manual