Remove building with NOCRYPTO option
[minix3.git] / lib / libm / src / s_cbrtf.c
blob83acbde3be655a29d7e112e9e4693eed87eda26f
1 /* s_cbrtf.c -- float version of s_cbrt.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
3 */
5 /*
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
12 * is preserved.
13 * ====================================================
16 #include <sys/cdefs.h>
17 #if defined(LIBM_SCCS) && !defined(lint)
18 __RCSID("$NetBSD: s_cbrtf.c,v 1.7 2002/05/26 22:01:54 wiz Exp $");
19 #endif
21 #include "math.h"
22 #include "math_private.h"
24 /* cbrtf(x)
25 * Return cube root of x
27 static const unsigned
28 B1 = 709958130, /* B1 = (84+2/3-0.03306235651)*2**23 */
29 B2 = 642849266; /* B2 = (76+2/3-0.03306235651)*2**23 */
31 static const float
32 C = 5.4285717010e-01, /* 19/35 = 0x3f0af8b0 */
33 D = -7.0530611277e-01, /* -864/1225 = 0xbf348ef1 */
34 E = 1.4142856598e+00, /* 99/70 = 0x3fb50750 */
35 F = 1.6071428061e+00, /* 45/28 = 0x3fcdb6db */
36 G = 3.5714286566e-01; /* 5/14 = 0x3eb6db6e */
38 float
39 cbrtf(float x)
41 float r,s,t;
42 int32_t hx;
43 u_int32_t sign;
44 u_int32_t high;
46 GET_FLOAT_WORD(hx,x);
47 sign=hx&0x80000000; /* sign= sign(x) */
48 hx ^=sign;
49 if(hx>=0x7f800000) return(x+x); /* cbrt(NaN,INF) is itself */
50 if(hx==0)
51 return(x); /* cbrt(0) is itself */
53 SET_FLOAT_WORD(x,hx); /* x <- |x| */
54 /* rough cbrt to 5 bits */
55 if(hx<0x00800000) /* subnormal number */
56 {SET_FLOAT_WORD(t,0x4b800000); /* set t= 2**24 */
57 t*=x; GET_FLOAT_WORD(high,t); SET_FLOAT_WORD(t,high/3+B2);
59 else
60 SET_FLOAT_WORD(t,hx/3+B1);
63 /* new cbrt to 23 bits */
64 r=t*t/x;
65 s=C+r*t;
66 t*=G+F/(s+E+D/s);
68 /* retore the sign bit */
69 GET_FLOAT_WORD(high,t);
70 SET_FLOAT_WORD(t,high|sign);
71 return(t);