man3/catanh.3

   1 .\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
   2 .\" Distributed under GPL
   3 .\"
   4 .TH CATANH 3 2007-12-26 "" "Linux Programmer's Manual"
   5 .SH NAME
   6 catanh, catanhf, catanhl \- complex arc tangents hyperbolic
   7 .SH SYNOPSIS
   8 .B #include <complex.h>
   9 .sp
  10 .BI "double complex catanh(double complex " z );
  11 .br
  12 .BI "float complex catanhf(float complex " z );
  13 .br
  14 .BI "long double complex catanhl(long double complex " z );
  15 .sp
  16 Link with \fI\-lm\fP.
  17 .SH DESCRIPTION
  18 The
  19 .BR catanh ()
  20 function calculates the complex arc hyperbolic tangent of
  21 .IR z .
  22 If \fIy\ =\ catanh(z)\fP, then \fIz\ =\ ctanh(y)\fP.
  23 The imaginary part of
  24 .I y
  25 is chosen in the interval [\-pi/2,pi/2].
  26 .LP
  27 One has:
  28 .nf
  29
  30     catanh(z) = 0.5 * clog((1 + z) / (1 \- z))
  31 .fi
  32 .SH "CONFORMING TO"
  33 C99
  34 .SH "SEE ALSO"
  35 .BR atanh (3),
  36 .BR cabs (3),
  37 .BR cimag (3),
  38 .BR complex (7)