.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
.\" Distributed under GPL
.\"
.TH CATAN 3 2002-07-28 "" "complex math routines"
.SH NAME
catan, catanf, catanl \- complex arc tangents 
.SH SYNOPSIS
.B #include <complex.h>
.sp
.BI "double complex catan(double complex " z ); 
.br
.BI "float complex catanf(float complex " z ); 
.br
.BI "long double complex catanl(long double complex " z ); 
.sp
Link with \-lm.
.SH DESCRIPTION
The
.BR catan ()
function calculates the complex atan().
If y = catan(z), then z = ctan(y).
The real part of y is chosen in the interval [\-pi/2,pi/2].
.LP
One has
catan(z) = 1/2i clog((1+iz)/(1\-iz)).
.SH "CONFORMING TO"
C99
.SH "SEE ALSO"
.BR ccos (3),
.BR clog (3),
.BR complex (5)