.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
.\"
.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
.\" Distributed under GPL
.\" %%%LICENSE_END
.\"
.TH CASIN 3 2008-08-11 "" "Linux Programmer's Manual"
.SH NAME
casin, casinf, casinl \- complex arc sine
.SH SYNOPSIS
.B #include <complex.h>
.sp
.BI "double complex casin(double complex " z );
.br
.BI "float complex casinf(float complex " z );
.br
.BI "long double complex casinl(long double complex " z );
.sp
Link with \fI\-lm\fP.
.SH DESCRIPTION
The
.BR casin ()
function calculates the complex arc sine of
.IR z .
If \fIy\ =\ casin(z)\fP, then \fIz\ =\ csin(y)\fP.
The real part of
.I y
is chosen in the interval [\-pi/2,pi/2].
.LP
One has:
.nf

    casin(z) = \-i clog(iz + csqrt(1 \- z * z))
.fi
.SH VERSIONS
These functions first appeared in glibc in version 2.1.
.SH CONFORMING TO
C99.
.SH SEE ALSO
.BR clog (3),
.BR csin (3),
.BR complex (7)
.SH COLOPHON
This page is part of release 3.74 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%http://www.kernel.org/doc/man\-pages/.