/*--------------------------------------------------------------------

 *© Portions copyright (c) 2006 Nokia Corporation.  All rights reserved.

 *--------------------------------------------------------------------

*/

/*

 e_acosf.c -- float version of e_acos.c.

 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.

 */

/*

 * ====================================================

 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.

 *

 * Developed at SunPro, a Sun Microsystems, Inc. business.

 * Permission to use, copy, modify, and distribute this

 * software is freely granted, provided that this notice

 * is preserved.

 * ====================================================

 */

#ifndef __SYMBIAN32__

#ifndef lint

static char rcsid[] = "$FreeBSD: src/lib/msun/src/e_acosf.c,v 1.7 2002/05/28 17:03:12 alfred Exp $";

#endif

#endif //__SYMBIAN32__

#include <math.h>

#include "math_private.h"

static const float

one =  1.0000000000e+00, /* 0x3F800000 */

pi =  3.1415925026e+00, /* 0x40490fda */

pio2_hi =  1.5707962513e+00, /* 0x3fc90fda */

pio2_lo =  7.5497894159e-08, /* 0x33a22168 */

pS0 =  1.6666667163e-01, /* 0x3e2aaaab */

pS1 = -3.2556581497e-01, /* 0xbea6b090 */

pS2 =  2.0121252537e-01, /* 0x3e4e0aa8 */

pS3 = -4.0055535734e-02, /* 0xbd241146 */

pS4 =  7.9153501429e-04, /* 0x3a4f7f04 */

pS5 =  3.4793309169e-05, /* 0x3811ef08 */

qS1 = -2.4033949375e+00, /* 0xc019d139 */

qS2 =  2.0209457874e+00, /* 0x4001572d */

qS3 = -6.8828397989e-01, /* 0xbf303361 */

qS4 =  7.7038154006e-02; /* 0x3d9dc62e */

EXPORT_C float __ieee754_acosf(float x)

{

	float z,p,q,r,w,s,c,df;

	int32_t hx,ix;

	GET_FLOAT_WORD(hx,x);

	ix = hx&0x7fffffff;

	if(ix==0x3f800000) {		/* |x|==1 */

	    if(hx>0) return 0.0;	/* acos(1) = 0  */

	    else return pi+(float)2.0*pio2_lo;	/* acos(-1)= pi */

	} else if(ix>0x3f800000) {	/* |x| >= 1 */

	    return (x-x)/(x-x);		/* acos(|x|>1) is NaN */

	}

	if(ix<0x3f000000) {	/* |x| < 0.5 */

	    if(ix<=0x23000000) return pio2_hi+pio2_lo;/*if|x|<2**-57*/

	    z = x*x;

	    p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));

	    q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));

	    r = p/q;

	    return pio2_hi - (x - (pio2_lo-x*r));

	} else  if (hx<0) {		/* x < -0.5 */

	    z = (one+x)*(float)0.5;

	    p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));

	    q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));

	    s = __ieee754_sqrtf(z);

	    r = p/q;

	    w = r*s-pio2_lo;

	    return pi - (float)2.0*(s+w);

	} else {			/* x > 0.5 */

	    int32_t idf;

	    z = (one-x)*(float)0.5;

	    s = __ieee754_sqrtf(z);

	    df = s;

	    GET_FLOAT_WORD(idf,df);

	    SET_FLOAT_WORD(df,idf&0xfffff000);

	    c  = (z-df*df)/(s+df);

	    p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));

	    q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));

	    r = p/q;

	    w = r*s+c;

	    return (float)2.0*(df+w);

	}

}