/*	@(#)asin.c	1.12	*//*LINTLIBRARY*//* *	C program for double-precision asin/acos. *	Returns EDOM error and value 0 if |argument| > 1. *	Algorithm and coefficients from Cody and Waite (1980). *	Calls sqrt if |argument| > 0.5. */#include <math.h>#include <values.h>#include <errno.h>doubleasin(x)double x;{	extern double asin_acos();	return (asin_acos(x, 0));}static doubleasin_acos(x, acosflag)register double x;int acosflag;{	register double y;	register int neg = 0, large = 0;	struct exception exc;		exc.arg1 = x;	if (x < 0) {		x = -x;		neg++;	}	if (x > 1) {		exc.type = DOMAIN;		exc.name = acosflag ? "acos" : "asin";		exc.retval = 0.0;		if (!matherr(&exc)) {			(void) write(2, exc.name, 4);			(void) write(2, ": DOMAIN error\n", 15);			errno = EDOM;		}		return (exc.retval);	}	if (x > X_EPS) { /* skip for efficiency and to prevent underflow */		static double p[] = {			-0.69674573447350646411e0,			 0.10152522233806463645e2,			-0.39688862997504877339e2,			 0.57208227877891731407e2,			-0.27368494524164255994e2,		}, q[] = {			 1.0,			-0.23823859153670238830e2,			 0.15095270841030604719e3,			-0.38186303361750149284e3,			 0.41714430248260412556e3,			-0.16421096714498560795e3,		};		if (x <= 0.5)			y = x * x;		else {			large++;			y = 0.5 - 0.5 * x;			x = -sqrt(y);			x += x;		}		x += x * y * _POLY4(y, p)/_POLY5(y, q);	}	if (acosflag) {		if (!neg)			x = -x;		return (!large ? M_PI_2 + x : neg ? M_PI + x : x);	}	if (large)		x += M_PI_2;	return (neg ? -x : x);}doubleacos(x)double x;{	return (asin_acos(x, 1));}