.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
.\"
.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
.\" Distributed under GPL
.\" %%%LICENSE_END
.\"
.TH CASIN 3 2015-04-19 "" "Linux Programmer's Manual"
.SH NAME
casin, casinf, casinl \- complex arc sine
.SH SYNOPSIS
.B #include <complex.h>
.PP
.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 );
.PP
Link with \fI\-lm\fP.
.SH DESCRIPTION
These functions calculate 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].
.PP
One has:
.PP
.nf
    casin(z) = \-i clog(iz + csqrt(1 \- z * z))
.fi
.SH VERSIONS
These functions first appeared in glibc in version 2.1.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbw28 lb lb
l l l.
Interface	Attribute	Value
T{
.BR casin (),
.BR casinf (),
.BR casinl ()
T}	Thread safety	MT-Safe
.TE
.SH CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
.SH SEE ALSO
.BR clog (3),
.BR csin (3),
.BR complex (7)
.SH COLOPHON
This page is part of release 5.04 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
\%https://www.kernel.org/doc/man\-pages/.