On success, these functions return the principal value of the arc sine of
.IR x
in radians; the return value is in the range [\-pi/2,\ pi/2].
-
+.PP
If
.I x
is a NaN, a NaN is returned.
-
+.PP
If
.I x
is +0 (\-0),
+0 (\-0) is returned.
-
+.PP
If
.I x
is outside the range [\-1,\ 1],
.TE
.SH CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
-
+.PP
The variant returning
.I double
also conforms to