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.\"     from: @(#)asin.3	5.1 (Berkeley) 5/2/91
.\" $FreeBSD: src/lib/msun/man/asin.3,v 1.15 2005/01/14 23:28:28 das Exp $
.\"
.Dd January 14, 2005
.Dt ASIN 3
.Os
.Sh NAME
.Nm asin ,
.Nm asinf
.Nd arc sine functions
.Sh LIBRARY
.Lb libm
.Sh SYNOPSIS
.In math.h
.Ft double
.Fn asin "double x"
.Ft float
.Fn asinf "float x"
.Sh DESCRIPTION
The
.Fn asin
and the
.Fn asinf
functions compute the principal value of the arc sine of
.Fa x .
A domain error occurs for arguments not in the range
.Bq -1 , +1 .
For a discussion of error due to roundoff, see
.Xr math 3 .
.Sh RETURN VALUES
The
.Fn asin
and the
.Fn asinf
functions return the arc sine in the range
.Bk -words
.Bq -\*(Pi/2 , +\*(Pi/2
.Ek
radians.
If:
.Bd -unfilled -offset indent
.Pf \&| Ns Ar x Ns \&| > 1
.Ed
.Pp
.Fn asin x
raises an invalid exception and returns an \*(Na.
.Sh SEE ALSO
.Xr acos 3 ,
.Xr atan 3 ,
.Xr atan2 3 ,
.Xr cos 3 ,
.Xr cosh 3 ,
.Xr fenv 3 ,
.Xr math 3 ,
.Xr sin 3 ,
.Xr sinh 3 ,
.Xr tan 3 ,
.Xr tanh 3
.Sh STANDARDS
The
.Fn asin
function conforms to
.St -isoC .