CLOG(3) Linux Programmer s Manual 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 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.


SEE ALSO cabs(3), cexp(3), clog10(3), complex(7)

COLOPHON This page is part of release 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at

2008-08-11 CLOG(3)