88 lines
2.2 KiB
C
Executable File
88 lines
2.2 KiB
C
Executable File
/* sincosf.c: Computes sin or cos of a 32-bit float as outlined in [1]
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Copyright (C) 2001, 2002 Jesus Calvino-Fraga, jesusc@ieee.org
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/* [1] William James Cody and W. M. Waite. _Software manual for the
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elementary functions_, Englewood Cliffs, N.J.:Prentice-Hall, 1980. */
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/* Version 1.0 - Initial release */
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#include "math.h"
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#include "errno.h"
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#include "stdbool.h"
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#define r1 -0.1666665668E+0
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#define r2 0.8333025139E-2
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#define r3 -0.1980741872E-3
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#define r4 0.2601903036E-5
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/* PI=C1+C2 */
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#define C1 3.140625
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#define C2 9.676535897E-4
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/*A reasonable value for YMAX is the int part of PI*B**(t/2)=3.1416*2**(12)*/
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#define YMAX 12867.0
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float sincosf(const float x, const int iscos)
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{
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float y, f, r, g, XN;
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int N;
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BOOL sign;
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if(iscos)
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{
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y=fabsf(x)+HALF_PI;
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sign=0;
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}
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else
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{
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if(x<0.0)
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{ y=-x; sign=1; }
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else
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{ y=x; sign=0; }
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}
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if(y>YMAX)
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{
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errno=ERANGE;
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return 0.0;
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}
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/*Round y/PI to the nearest integer*/
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N=((y*iPI)+0.5); /*y is positive*/
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/*If N is odd change sign*/
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if(N&1) sign=!sign;
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XN=N;
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/*Cosine required? (is done here to keep accuracy)*/
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if(iscos) XN-=0.5;
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y=fabsf(x);
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r=(int)y;
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g=y-r;
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f=((r-XN*C1)+g)-XN*C2;
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g=f*f;
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if(g>EPS2) //Used to be if(fabsf(f)>EPS)
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{
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r=(((r4*g+r3)*g+r2)*g+r1)*g;
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f+=f*r;
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}
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return (sign?-f:f);
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}
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