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