.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
.\" Distributed under GPL
.\"
.TH CASIN 3 2002-07-28 "" "complex math routines"
.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 \-lm.
.SH DESCRIPTION
The 
.BR casin () 
function calculates the complex asin().
If y = casin(z), then z = csin(y).
The real part of y is chosen in the interval [\-pi/2,pi/2].
.LP
One has
casin(z) = \-i clog(iz+csqrt(1\-z*z)).
.SH "CONFORMING TO"
C99
.SH "SEE ALSO"
.BR ccos (3),
.BR clog (3),
.BR complex (5)