first commit of the new libm!

[musl] / src / math / e_log10.c

diff --git a/src/math/e_log10.c b/src/math/e_log10.c
deleted file mode 100644 (file)
index 3be179f..0000000
--- a/src/math/e_log10.c
+++ /dev/null
@@ -1,83 +0,0 @@
-
-/* @(#)e_log10.c 1.3 95/01/18 */
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunSoft, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice 
- * is preserved.
- * ====================================================
- */
-
-/* log10(x)
- * Return the base 10 logarithm of x
- * 
- * Method :
- *      Let log10_2hi = leading 40 bits of log10(2) and
- *          log10_2lo = log10(2) - log10_2hi,
- *          ivln10   = 1/log(10) rounded.
- *      Then
- *              n = ilogb(x), 
- *              if(n<0)  n = n+1;
- *              x = scalbn(x,-n);
- *              log10(x) := n*log10_2hi + (n*log10_2lo + ivln10*log(x))
- *
- * Note 1:
- *      To guarantee log10(10**n)=n, where 10**n is normal, the rounding 
- *      mode must set to Round-to-Nearest.
- * Note 2:
- *      [1/log(10)] rounded to 53 bits has error  .198   ulps;
- *      log10 is monotonic at all binary break points.
- *
- * Special cases:
- *      log10(x) is NaN with signal if x < 0; 
- *      log10(+INF) is +INF with no signal; log10(0) is -INF with signal;
- *      log10(NaN) is that NaN with no signal;
- *      log10(10**N) = N  for N=0,1,...,22.
- *
- * 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"
-
-static const double
-two54      =  1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
-ivln10     =  4.34294481903251816668e-01, /* 0x3FDBCB7B, 0x1526E50E */
-log10_2hi  =  3.01029995663611771306e-01, /* 0x3FD34413, 0x509F6000 */
-log10_2lo  =  3.69423907715893078616e-13; /* 0x3D59FEF3, 0x11F12B36 */
-
-static const double zero   =  0.0;
-
-double
-log10(double x)
-{
-        double y,z;
-        int32_t i,k,hx;
-        uint32_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) 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;
-        i  = ((uint32_t)k&0x80000000)>>31;
-        hx = (hx&0x000fffff)|((0x3ff-i)<<20);
-        y  = (double)(k+i);
-        SET_HIGH_WORD(x,hx);
-        z  = y*log10_2lo + ivln10*log(x);
-        return  z+y*log10_2hi;
-}