]>
sourceware.org Git - glibc.git/blob - sysdeps/ieee754/flt-32/k_tanf.c
1 /* k_tanf.c -- float version of k_tan.c
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
13 * ====================================================
16 #if defined(LIBM_SCCS) && !defined(lint)
17 static char rcsid
[] = "$NetBSD: k_tanf.c,v 1.4 1995/05/10 20:46:39 jtc Exp $";
22 #include <math_private.h>
23 #include <math-underflow.h>
25 one
= 1.0000000000e+00, /* 0x3f800000 */
26 pio4
= 7.8539812565e-01, /* 0x3f490fda */
27 pio4lo
= 3.7748947079e-08, /* 0x33222168 */
29 3.3333334327e-01, /* 0x3eaaaaab */
30 1.3333334029e-01, /* 0x3e088889 */
31 5.3968254477e-02, /* 0x3d5d0dd1 */
32 2.1869488060e-02, /* 0x3cb327a4 */
33 8.8632395491e-03, /* 0x3c11371f */
34 3.5920790397e-03, /* 0x3b6b6916 */
35 1.4562094584e-03, /* 0x3abede48 */
36 5.8804126456e-04, /* 0x3a1a26c8 */
37 2.4646313977e-04, /* 0x398137b9 */
38 7.8179444245e-05, /* 0x38a3f445 */
39 7.1407252108e-05, /* 0x3895c07a */
40 -1.8558637748e-05, /* 0xb79bae5f */
41 2.5907305826e-05, /* 0x37d95384 */
44 float __kernel_tanf(float x
, float y
, int iy
)
49 ix
= hx
&0x7fffffff; /* high word of |x| */
50 if(ix
<0x39000000) /* x < 2**-13 */
51 {if((int)x
==0) { /* generate inexact */
52 if((ix
|(iy
+1))==0) return one
/fabsf(x
);
55 math_check_force_underflow (x
);
62 if(ix
>=0x3f2ca140) { /* |x|>=0.6744 */
63 if(hx
<0) {x
= -x
; y
= -y
;}
67 if (fabsf (x
) < 0x1p
-13f
)
68 return (1 - ((hx
>> 30) & 2)) * iy
* (1.0f
- 2 * iy
* x
);
72 /* Break x^5*(T[1]+x^2*T[2]+...) into
73 * x^5(T[1]+x^4*T[3]+...+x^20*T[11]) +
74 * x^5(x^2*(T[2]+x^4*T[4]+...+x^22*[T12]))
76 r
= T
[1]+w
*(T
[3]+w
*(T
[5]+w
*(T
[7]+w
*(T
[9]+w
*T
[11]))));
77 v
= z
*(T
[2]+w
*(T
[4]+w
*(T
[6]+w
*(T
[8]+w
*(T
[10]+w
*T
[12])))));
79 r
= y
+ z
*(s
*(r
+v
)+y
);
84 return (float)(1-((hx
>>30)&2))*(v
-(float)2.0*(x
-(w
*w
/(w
+v
)-r
)));
87 else { /* if allow error up to 2 ulp,
88 simply return -1.0/(x+r) here */
89 /* compute -1.0/(x+r) accurately */
94 SET_FLOAT_WORD(z
,i
&0xfffff000);
95 v
= r
-(z
- x
); /* z+v = r+x */
96 t
= a
= -(float)1.0/w
; /* a = -1.0/w */
98 SET_FLOAT_WORD(t
,i
&0xfffff000);
This page took 0.042659 seconds and 5 git commands to generate.