man3/catan.3

   1 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
   2 .\" Distributed under GPL
   3 .\"
   4 .TH CATAN 3 2007-12-26 "" "Linux Programmer's Manual"
   5 .SH NAME
   6 catan, catanf, catanl \- complex arc tangents
   7 .SH SYNOPSIS
   8 .B #include <complex.h>
   9 .sp
  10 .BI "double complex catan(double complex " z );
  11 .br
  12 .BI "float complex catanf(float complex " z );
  13 .br
  14 .BI "long double complex catanl(long double complex " z );
  15 .sp
  16 Link with \fI\-lm\fP.
  17 .SH DESCRIPTION
  18 The
  19 .BR catan ()
  20 function calculates the complex arc tangent of
  21 .IR z .
  22 If \fIy\ =\ catan(z)\fP, then \fIz\ =\ ctan(y)\fP.
  23 The real part of y is chosen in the interval [\-pi/2,pi/2].
  24 .LP
  25 One has:
  26 .nf
  27
  28     catan(z) = 1 / 2i clog((1 + iz) / (1 \- iz))
  29 .fi
  30 .SH "CONFORMING TO"
  31 C99
  32 .SH "SEE ALSO"
  33 .BR ccos (3),
  34 .BR clog (3),
  35 .BR complex (7)