clog(3) — Linux manual page


CLOG(3)                 Linux Programmer's Manual                CLOG(3)

NAME         top

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

SYNOPSIS         top

       #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         top

       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.

VERSIONS         top

       These functions first appeared in glibc in version 2.1.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │Interface                             Attribute     Value   │
       │clog(), clogf(), clogl()              │ Thread safety │ MT-Safe │

CONFORMING TO         top

       C99, POSIX.1-2001, POSIX.1-2008.

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.13 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at

                               2021-03-22                        CLOG(3)

Pages that refer to this page: cacos(3)casin(3)catan(3)cexp(3)clog10(3)clog2(3)log(3)complex(7)