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Diffstat (limited to 'StdLib/LibC/Math/e_log.c')
| -rw-r--r-- | StdLib/LibC/Math/e_log.c | 155 |
1 files changed, 0 insertions, 155 deletions
diff --git a/StdLib/LibC/Math/e_log.c b/StdLib/LibC/Math/e_log.c deleted file mode 100644 index 979b7f9421..0000000000 --- a/StdLib/LibC/Math/e_log.c +++ /dev/null @@ -1,155 +0,0 @@ -/** @file
- Compute the logrithm of x.
-
- Copyright (c) 2010 - 2011, Intel Corporation. All rights reserved.<BR>
- This program and the accompanying materials are licensed and made available under
- the terms and conditions of the BSD License that accompanies this distribution.
- The full text of the license may be found at
- http://opensource.org/licenses/bsd-license.
-
- THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
- WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
-
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunPro, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice
- * is preserved.
- * ====================================================
-
- e_log.c 5.1 93/09/24
- NetBSD: e_log.c,v 1.12 2002/05/26 22:01:51 wiz Exp
-**/
-#include <LibConfig.h>
-#include <sys/EfiCdefs.h>
-
-#if defined(_MSC_VER) /* Handle Microsoft VC++ compiler specifics. */
- // potential divide by 0 -- near line 118, (x-x)/zero is on purpose
- #pragma warning ( disable : 4723 )
-#endif
-
-/* __ieee754_log(x)
- * Return the logrithm of x
- *
- * Method :
- * 1. Argument Reduction: find k and f such that
- * x = 2^k * (1+f),
- * where sqrt(2)/2 < 1+f < sqrt(2) .
- *
- * 2. Approximation of log(1+f).
- * Let s = f/(2+f) ; based on log(1+f) = log(1+s) - log(1-s)
- * = 2s + 2/3 s**3 + 2/5 s**5 + .....,
- * = 2s + s*R
- * We use a special Reme algorithm on [0,0.1716] to generate
- * a polynomial of degree 14 to approximate R The maximum error
- * of this polynomial approximation is bounded by 2**-58.45. In
- * other words,
- * 2 4 6 8 10 12 14
- * R(z) ~ Lg1*s +Lg2*s +Lg3*s +Lg4*s +Lg5*s +Lg6*s +Lg7*s
- * (the values of Lg1 to Lg7 are listed in the program)
- * and
- * | 2 14 | -58.45
- * | Lg1*s +...+Lg7*s - R(z) | <= 2
- * | |
- * Note that 2s = f - s*f = f - hfsq + s*hfsq, where hfsq = f*f/2.
- * In order to guarantee error in log below 1ulp, we compute log
- * by
- * log(1+f) = f - s*(f - R) (if f is not too large)
- * log(1+f) = f - (hfsq - s*(hfsq+R)). (better accuracy)
- *
- * 3. Finally, log(x) = k*ln2 + log(1+f).
- * = k*ln2_hi+(f-(hfsq-(s*(hfsq+R)+k*ln2_lo)))
- * Here ln2 is split into two floating point number:
- * ln2_hi + ln2_lo,
- * where n*ln2_hi is always exact for |n| < 2000.
- *
- * Special cases:
- * log(x) is NaN with signal if x < 0 (including -INF) ;
- * log(+INF) is +INF; log(0) is -INF with signal;
- * log(NaN) is that NaN with no signal.
- *
- * Accuracy:
- * according to an error analysis, the error is always less than
- * 1 ulp (unit in the last place).
- *
- * Constants:
- * The hexadecimal values are the intended ones for the following
- * constants. The decimal values may be used, provided that the
- * compiler will convert from decimal to binary accurately enough
- * to produce the hexadecimal values shown.
- */
-
-#include "math.h"
-#include "math_private.h"
-#include <errno.h>
-
-static const double
-ln2_hi = 6.93147180369123816490e-01, /* 3fe62e42 fee00000 */
-ln2_lo = 1.90821492927058770002e-10, /* 3dea39ef 35793c76 */
-two54 = 1.80143985094819840000e+16, /* 43500000 00000000 */
-Lg1 = 6.666666666666735130e-01, /* 3FE55555 55555593 */
-Lg2 = 3.999999999940941908e-01, /* 3FD99999 9997FA04 */
-Lg3 = 2.857142874366239149e-01, /* 3FD24924 94229359 */
-Lg4 = 2.222219843214978396e-01, /* 3FCC71C5 1D8E78AF */
-Lg5 = 1.818357216161805012e-01, /* 3FC74664 96CB03DE */
-Lg6 = 1.531383769920937332e-01, /* 3FC39A09 D078C69F */
-Lg7 = 1.479819860511658591e-01; /* 3FC2F112 DF3E5244 */
-
-static const double zero = 0.0;
-
-double
-__ieee754_log(double x)
-{
- double hfsq,f,s,z,R,w,t1,t2,dk;
- int32_t k,hx,i,j;
- u_int32_t lx;
-
- EXTRACT_WORDS(hx,lx,x);
-
- k=0;
- if (hx < 0x00100000) { /* x < 2**-1022 */
- if (((hx&0x7fffffff)|lx)==0)
- return -two54/zero; /* log(+-0)=-inf */
- if (hx<0) {
- errno = EDOM;
- return (x-x)/zero; /* log(-#) = NaN */
- }
- k -= 54; x *= two54; /* subnormal number, scale up x */
- GET_HIGH_WORD(hx,x);
- }
- if (hx >= 0x7ff00000) return x+x;
- k += (hx>>20)-1023;
- hx &= 0x000fffff;
- i = (hx+0x95f64)&0x100000;
- SET_HIGH_WORD(x,hx|(i^0x3ff00000)); /* normalize x or x/2 */
- k += (i>>20);
- f = x-1.0;
- if((0x000fffff&(2+hx))<3) { /* |f| < 2**-20 */
- if(f==zero) { if(k==0) return zero; else {dk=(double)k;
- return dk*ln2_hi+dk*ln2_lo;}
- }
- R = f*f*(0.5-0.33333333333333333*f);
- if(k==0) return f-R; else {dk=(double)k;
- return dk*ln2_hi-((R-dk*ln2_lo)-f);}
- }
- s = f/(2.0+f);
- dk = (double)k;
- z = s*s;
- i = hx-0x6147a;
- w = z*z;
- j = 0x6b851-hx;
- t1= w*(Lg2+w*(Lg4+w*Lg6));
- t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7)));
- i |= j;
- R = t2+t1;
- if(i>0) {
- hfsq=0.5*f*f;
- if(k==0) return f-(hfsq-s*(hfsq+R)); else
- return dk*ln2_hi-((hfsq-(s*(hfsq+R)+dk*ln2_lo))-f);
- } else {
- if(k==0) return f-s*(f-R); else
- return dk*ln2_hi-((s*(f-R)-dk*ln2_lo)-f);
- }
-}
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