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Annotation of 43BSDTahoe/usr.lib/libm/common/sincos.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1987 Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms are permitted
        !             6:  * provided that the above copyright notice and this paragraph are
        !             7:  * duplicated in all such forms and that any documentation,
        !             8:  * advertising materials, and other materials related to such
        !             9:  * distribution and use acknowledge that the software was developed
        !            10:  * by the University of California, Berkeley.  The name of the
        !            11:  * University may not be used to endorse or promote products derived
        !            12:  * from this software without specific prior written permission.
        !            13:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            14:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            15:  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            16:  *
        !            17:  * All recipients should regard themselves as participants in an ongoing
        !            18:  * research project and hence should feel obligated to report their
        !            19:  * experiences (good or bad) with these elementary function codes, using
        !            20:  * the sendbug(8) program, to the authors.
        !            21:  */
        !            22: 
        !            23: #ifndef lint
        !            24: static char sccsid[] = "@(#)sincos.c   5.3 (Berkeley) 6/30/88";
        !            25: #endif /* not lint */
        !            26: 
        !            27: #include "trig.h"
        !            28: double
        !            29: sin(x)
        !            30: double x;
        !            31: {
        !            32:        double a,c,z;
        !            33: 
        !            34:         if(!finite(x))         /* sin(NaN) and sin(INF) must be NaN */
        !            35:                return x-x;
        !            36:        x=drem(x,PI2);          /* reduce x into [-PI,PI] */
        !            37:        a=copysign(x,one);
        !            38:        if (a >= PIo4) {
        !            39:                if(a >= PI3o4)          /* ... in [3PI/4,PI] */
        !            40:                        x = copysign((a = PI-a),x);
        !            41:                else {                  /* ... in [PI/4,3PI/4]  */
        !            42:                        a = PIo2-a;             /* rtn. sign(x)*C(PI/2-|x|) */
        !            43:                        z = a*a;
        !            44:                        c = cos__C(z);
        !            45:                        z *= half;
        !            46:                        a = (z >= thresh ? half-((z-half)-c) : one-(z-c));
        !            47:                        return copysign(a,x);
        !            48:                }
        !            49:        }
        !            50: 
        !            51:        if (a < small) {                /* rtn. S(x) */
        !            52:                big+a;
        !            53:                return x;
        !            54:        }
        !            55:        return x+x*sin__S(x*x);
        !            56: }
        !            57: 
        !            58: double
        !            59: cos(x) 
        !            60: double x;
        !            61: {
        !            62:        double a,c,z,s = 1.0;
        !            63: 
        !            64:        if(!finite(x))          /* cos(NaN) and cos(INF) must be NaN */
        !            65:                return x-x;
        !            66:        x=drem(x,PI2);          /* reduce x into [-PI,PI] */
        !            67:        a=copysign(x,one);
        !            68:        if (a >= PIo4) {
        !            69:                if (a >= PI3o4) {       /* ... in [3PI/4,PI] */
        !            70:                        a = PI-a;
        !            71:                        s = negone;
        !            72:                }
        !            73:                else {                  /* ... in [PI/4,3PI/4] */
        !            74:                        a = PIo2-a;
        !            75:                        return a+a*sin__S(a*a); /* rtn. S(PI/2-|x|) */ 
        !            76:                }
        !            77:        }
        !            78:        if (a < small) {
        !            79:                big+a;
        !            80:                return s;               /* rtn. s*C(a) */
        !            81:        }
        !            82:        z = a*a;
        !            83:        c = cos__C(z);
        !            84:        z *= half;
        !            85:        a = (z >= thresh ? half-((z-half)-c) : one-(z-c));
        !            86:        return copysign(a,s);
        !            87: }

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