Linux manual pages Section 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);
 
[Note] Note

Link with −lm.

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.

VERSIONS

These functions first appeared in glibc in version 2.1.

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

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

CONFORMING TO

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

SEE ALSO

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

COLOPHON

This page is part of release 4.07 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 https://www.kernel.org/doc/man−pages/.


  Copyright 2002 Walter Harms (walter.harmsinformatik.uni-oldenburg.de)

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