.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
.\" Distributed under GPL
.\"
.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 3.44 of the Linux
.I man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.