k_tanf.c revision 152713
1202317Sbrueffer/* k_tanf.c -- float version of k_tan.c 2202317Sbrueffer * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 3202317Sbrueffer */ 4202317Sbrueffer 5202317Sbrueffer/* 6202317Sbrueffer * ==================================================== 7202317Sbrueffer * Copyright 2004 Sun Microsystems, Inc. All Rights Reserved. 8202317Sbrueffer * 9202317Sbrueffer * Permission to use, copy, modify, and distribute this 10202317Sbrueffer * software is freely granted, provided that this notice 11202317Sbrueffer * is preserved. 12202317Sbrueffer * ==================================================== 13202317Sbrueffer */ 14202317Sbrueffer 15202317Sbrueffer#ifndef INLINE_KERNEL_TANF 16202317Sbrueffer#ifndef lint 17202317Sbruefferstatic char rcsid[] = "$FreeBSD: head/lib/msun/src/k_tanf.c 152713 2005-11-23 14:27:56Z bde $"; 18202317Sbrueffer#endif 19202317Sbrueffer#endif 20202317Sbrueffer 21202317Sbrueffer#include "math.h" 22202317Sbrueffer#include "math_private.h" 23202317Sbrueffer 24202317Sbruefferstatic const double 25202317Sbruefferpio4 = M_PI_4, 26202317Sbrueffer/* |tan(x)/x - t(x)| < 2**-29.1 (~[-1.72e-09, 1.719e-09]). */ 27202317SbruefferT[] = { 28202317Sbrueffer 0x1555545f8b54d0.0p-54, /* 0.333333104424423432022 */ 29202317Sbrueffer 0x111160cdc2c9af.0p-55, /* 0.133342838734802765499 */ 30202317Sbrueffer 0x1b9097e5693cd0.0p-57, /* 0.0538375346701457369036 */ 31202317Sbrueffer 0x173b2333895b6f.0p-58, /* 0.0226865291791357691353 */ 32202317Sbrueffer 0x19fcb197e825ab.0p-60, /* 0.00634450313965243938713 */ 33202317Sbrueffer 0x1d5f3701b44a27.0p-60, /* 0.00717088210082520490646 */ 34202317Sbrueffer}; 35202317Sbrueffer 36202317Sbrueffer#ifdef INLINE_KERNEL_TANF 37202317Sbruefferextern inline 38202317Sbrueffer#endif 39202317Sbruefferfloat 40202317Sbrueffer__kernel_tandf(double x, int iy) 41202317Sbrueffer{ 42202317Sbrueffer double z,r,v,w,s; 43202317Sbrueffer int32_t ix,hx; 44202317Sbrueffer 45202317Sbrueffer GET_FLOAT_WORD(hx,x); 46202317Sbrueffer ix = hx&0x7fffffff; 47202317Sbrueffer if(ix>=0x3f2ca140) { /* |x|>=0.67434 */ 48202317Sbrueffer if(hx<0) {x = -x;} 49202317Sbrueffer x = pio4-x; 50202317Sbrueffer } 51202317Sbrueffer z = x*x; 52202317Sbrueffer w = z*z; 53202317Sbrueffer /* Break x^5*(T[1]+x^2*T[2]+...) into 54202317Sbrueffer * x^5*(T[1]+x^4*T[3]+x^8*T[5]) + 55202317Sbrueffer * x^5*(x^2*(T[2]+x^4*T[4])) 56202317Sbrueffer */ 57202317Sbrueffer r = T[1]+w*(T[3]+w*T[5]); 58202317Sbrueffer v = z*(T[2]+w*T[4]); 59202317Sbrueffer s = z*x; 60202317Sbrueffer r = z*s*(r+v); 61202317Sbrueffer r += T[0]*s; 62202317Sbrueffer w = x+r; 63202317Sbrueffer if(ix>=0x3f2ca140) { 64202317Sbrueffer v = (double)iy; 65202317Sbrueffer return (double)(1-((hx>>30)&2))*(v-2.0*(x-(w*w/(w+v)-r))); 66202317Sbrueffer } 67202317Sbrueffer if(iy==1) return w; 68202317Sbrueffer else return -1.0/w; 69202317Sbrueffer} 70202317Sbrueffer