#ifndef lintstatic	char sccsid[] = "@(#)asin.c 1.1 92/07/30 SMI";#endif/* * Copyright (c) 1987 by Sun Microsystems, Inc. *//* asin(x) * Code originated from 4.3bsd. * Modified by K.C. Ng for SUN 4.0 libm. * Method :                   * *	asin(x) = atan2(x,sqrt(1-x*x)); for better accuracy, 1-x*x is  *		  computed as follows *			1-x*x                     if x <  0.5,  *			2*(1-|x|)-(1-|x|)*(1-|x|) if x >= 0.5. * * Special cases: *	if x is NaN, return x itself; *	if |x|>1, return NaN with invalid signal. * */#include <math.h>#include "libm.h"double asin(x)double x;{	double t,w;	w = fabs(x);	if (x!=x)		return x+x;	else if(w <= 0.5) {		if(w<1.0e-9) {dummy(1.0e9+w); return x;} else		return atan(x/sqrt(1.-x*x));	}	else if(w <  1.0) {		t = 1.0-w;		w = t+t;		return atan(x/sqrt(w-t*t));		}	else if(w == 1.0)		return atan2(x,0.0);	/* asin(+-1) =  +- PI/2 */	else 	{		/* |x| > 1 create invalid signal */		return SVID_libm_err(x,x,2);		}}static dummy(x)double x;{	return 1;}