Deleted Added
sdiff udiff text old ( 152870 ) new ( 152881 )
full compact
k_tanf.c (152870) k_tanf.c (152881)
1/* k_tanf.c -- float version of k_tan.c
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 * Optimized by Bruce D. Evans.
4 */
5
6/*
7 * ====================================================
8 * Copyright 2004 Sun Microsystems, Inc. All Rights Reserved.
9 *
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
12 * is preserved.
13 * ====================================================
14 */
15
16#ifndef INLINE_KERNEL_TANDF
17#ifndef lint
1/* k_tanf.c -- float version of k_tan.c
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 * Optimized by Bruce D. Evans.
4 */
5
6/*
7 * ====================================================
8 * Copyright 2004 Sun Microsystems, Inc. All Rights Reserved.
9 *
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
12 * is preserved.
13 * ====================================================
14 */
15
16#ifndef INLINE_KERNEL_TANDF
17#ifndef lint
18static char rcsid[] = "$FreeBSD: head/lib/msun/src/k_tanf.c 152870 2005-11-28 05:35:32Z bde $";
18static char rcsid[] = "$FreeBSD: head/lib/msun/src/k_tanf.c 152881 2005-11-28 11:46:20Z bde $";
19#endif
20#endif
21
22#include "math.h"
23#include "math_private.h"
24
25/* |tan(x)/x - t(x)| < 2**-25.5 (~[-2e-08, 2e-08]). */
26static const double

--- 7 unchanged lines hidden (view full) ---

34};
35
36#ifdef INLINE_KERNEL_TANDF
37extern inline
38#endif
39float
40__kernel_tandf(double x, int iy)
41{
19#endif
20#endif
21
22#include "math.h"
23#include "math_private.h"
24
25/* |tan(x)/x - t(x)| < 2**-25.5 (~[-2e-08, 2e-08]). */
26static const double

--- 7 unchanged lines hidden (view full) ---

34};
35
36#ifdef INLINE_KERNEL_TANDF
37extern inline
38#endif
39float
40__kernel_tandf(double x, int iy)
41{
42 double z,r,w,s;
42 double z,r,w,s,t,u;
43
44 z = x*x;
43
44 z = x*x;
45 w = z*z;
46 /* Break x^5*(T[1]+x^2*T[2]+...) into
47 * x^5*(T[1]+x^4*T[3]+x^8*T[5]) +
48 * x^5*(x^2*(T[2]+x^4*T[4]))
49 */
50 r = (T[1]+w*(T[3]+w*T[5])) + z*(T[2]+w*T[4]);
45 /*
46 * Split up the polynomial into small independent terms to give
47 * opportunities for parallel evaluation. The chosen splitting is
48 * micro-optimized for Athlons (XP, X64). It costs 2 multiplications
49 * relative to Horner's method on sequential machines.
50 *
51 * We add the small terms from lowest degree up for efficiency on
52 * non-sequential machines (the lowest degree terms tend to be ready
53 * earlier). Apart from this, we don't care about order of
54 * operations, and don't need to to care since we have precision to
55 * spare. However, the chosen splitting is good for accuracy too,
56 * and would give results as accurate as Horner's method if the
57 * small terms were added from highest degree down.
58 */
59 r = T[4]+z*T[5];
60 t = T[2]+z*T[3];
61 w = z*z;
51 s = z*x;
62 s = z*x;
52 r = (x+s*T[0])+(s*z)*r;
63 u = T[0]+z*T[1];
64 r = (x+s*u)+(s*w)*(t+w*r);
53 if(iy==1) return r;
54 else return -1.0/r;
55}
65 if(iy==1) return r;
66 else return -1.0/r;
67}