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/* kf_tan.c -- float version of k_tan.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.

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

 */

#include "fdlibm.h"

#ifdef __STDC__

static const float

#else

static float

#endif

one   =  1.0000000000e+00, /* 0x3f800000 */

pio4  =  7.8539812565e-01, /* 0x3f490fda */

pio4lo=  3.7748947079e-08, /* 0x33222168 */

T[] =  {

  3.3333334327e-01, /* 0x3eaaaaab */

  1.3333334029e-01, /* 0x3e088889 */

  5.3968254477e-02, /* 0x3d5d0dd1 */

  2.1869488060e-02, /* 0x3cb327a4 */

  8.8632395491e-03, /* 0x3c11371f */

  3.5920790397e-03, /* 0x3b6b6916 */

  1.4562094584e-03, /* 0x3abede48 */

  5.8804126456e-04, /* 0x3a1a26c8 */

  2.4646313977e-04, /* 0x398137b9 */

  7.8179444245e-05, /* 0x38a3f445 */

  7.1407252108e-05, /* 0x3895c07a */

 -1.8558637748e-05, /* 0xb79bae5f */

  2.5907305826e-05, /* 0x37d95384 */

};

#ifdef __STDC__

        float __kernel_tanf(float x, float y, int iy)

#else

        float __kernel_tanf(x, y, iy)

        float x,y; int iy;

#endif

{

        float z,r,v,w,s;

        __int32_t ix,hx;

        GET_FLOAT_WORD(hx,x);

        ix = hx&0x7fffffff;     /* high word of |x| */

        if(ix<0x31800000)                       /* x < 2**-28 */

            {if((int)x==0) {                     /* generate inexact */

                if((ix|(iy+1))==0) return one/fabsf(x);

                else return (iy==1)? x: -one/x;

            }

            }

        if(ix>=0x3f2ca140) {                    /* |x|>=0.6744 */

            if(hx<0) {x = -x; y = -y;}

            z = pio4-x;

            w = pio4lo-y;

            x = z+w; y = 0.0;

        }

        z       =  x*x;

        w       =  z*z;

    /* Break x^5*(T[1]+x^2*T[2]+...) into

     *    x^5(T[1]+x^4*T[3]+...+x^20*T[11]) +

     *    x^5(x^2*(T[2]+x^4*T[4]+...+x^22*[T12]))

     */

        r = T[1]+w*(T[3]+w*(T[5]+w*(T[7]+w*(T[9]+w*T[11]))));

        v = z*(T[2]+w*(T[4]+w*(T[6]+w*(T[8]+w*(T[10]+w*T[12])))));

        s = z*x;

        r = y + z*(s*(r+v)+y);

        r += T[0]*s;

        w = x+r;

        if(ix>=0x3f2ca140) {

            v = (float)iy;

            return (float)(1-((hx>>30)&2))*(v-(float)2.0*(x-(w*w/(w+v)-r)));

        }

        if(iy==1) return w;

        else {          /* if allow error up to 2 ulp,

                           simply return -1.0/(x+r) here */

     /*  compute -1.0/(x+r) accurately */

            float a,t;

            __int32_t i;

            z  = w;

            GET_FLOAT_WORD(i,z);

            SET_FLOAT_WORD(z,i&0xfffff000);

            v  = r-(z - x);     /* z+v = r+x */

            t = a  = -(float)1.0/w;     /* a = -1.0/w */

            GET_FLOAT_WORD(i,t);

            SET_FLOAT_WORD(t,i&0xfffff000);

            s  = (float)1.0+t*z;

            return t+a*(s+t*v);

        }

}