.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
.\" Distributed under GPL
.\"
.TH CLOG 3 2007-12-26 "" "Linux Programmer's Manual"
.SH NAME
clog, clogf, clogl \- natural logarithm of a complex number
.SH SYNOPSIS
.B #include <complex.h>
.sp
.BI "double complex clog(double complex " z );
.br
.BI "float complex clogf(float complex " z );
.br
.BI "long double complex clogl(long double complex " z );
.sp
Link with \fI\-lm\fP.
.SH DESCRIPTION
The logarithm
.BR clog ()
is the inverse function of the exponential
.BR cexp (3).
Thus, if \fIy\ =\ clog(z)\fP, then \fIz\ =\ cexp(y)\fP.
The imaginary part of
.I y
is chosen in the interval [\-pi,pi].
.LP
One has:
.nf

    clog(z) = log(cabs(z)) + I * carg(z)
.fi
.LP
Note that
.I z
close to zero will cause an overflow.
.SH "CONFORMING TO"
C99.
.SH "SEE ALSO"
.BR cabs (3),
.BR cexp (3),
.BR clog10 (3),
.BR complex (7)