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authorEric Andersen <andersen@codepoet.org>2001-11-22 14:04:29 +0000
committerEric Andersen <andersen@codepoet.org>2001-11-22 14:04:29 +0000
commit7ce331c01ce6eb7b3f5c715a38a24359da9c6ee2 (patch)
tree3a7e8476e868ae15f4da1b7ce26b2db6f434468c /libm/double/log.c
parentc117dd5fb183afb1a4790a6f6110d88704be6bf8 (diff)
Totally rework the math library, this time based on the MacOs X
math library (which is itself based on the math lib from FreeBSD). -Erik
Diffstat (limited to 'libm/double/log.c')
-rw-r--r--libm/double/log.c341
1 files changed, 0 insertions, 341 deletions
diff --git a/libm/double/log.c b/libm/double/log.c
deleted file mode 100644
index 2fdea17a7..000000000
--- a/libm/double/log.c
+++ /dev/null
@@ -1,341 +0,0 @@
-/* log.c
- *
- * Natural logarithm
- *
- *
- *
- * SYNOPSIS:
- *
- * double x, y, log();
- *
- * y = log( x );
- *
- *
- *
- * DESCRIPTION:
- *
- * Returns the base e (2.718...) logarithm of x.
- *
- * The argument is separated into its exponent and fractional
- * parts. If the exponent is between -1 and +1, the logarithm
- * of the fraction is approximated by
- *
- * log(1+x) = x - 0.5 x**2 + x**3 P(x)/Q(x).
- *
- * Otherwise, setting z = 2(x-1)/x+1),
- *
- * log(x) = z + z**3 P(z)/Q(z).
- *
- *
- *
- * ACCURACY:
- *
- * Relative error:
- * arithmetic domain # trials peak rms
- * IEEE 0.5, 2.0 150000 1.44e-16 5.06e-17
- * IEEE +-MAXNUM 30000 1.20e-16 4.78e-17
- * DEC 0, 10 170000 1.8e-17 6.3e-18
- *
- * In the tests over the interval [+-MAXNUM], the logarithms
- * of the random arguments were uniformly distributed over
- * [0, MAXLOG].
- *
- * ERROR MESSAGES:
- *
- * log singularity: x = 0; returns -INFINITY
- * log domain: x < 0; returns NAN
- */
-
-/*
-Cephes Math Library Release 2.8: June, 2000
-Copyright 1984, 1995, 2000 by Stephen L. Moshier
-*/
-
-#include <math.h>
-static char fname[] = {"log"};
-
-/* Coefficients for log(1+x) = x - x**2/2 + x**3 P(x)/Q(x)
- * 1/sqrt(2) <= x < sqrt(2)
- */
-#ifdef UNK
-static double P[] = {
- 1.01875663804580931796E-4,
- 4.97494994976747001425E-1,
- 4.70579119878881725854E0,
- 1.44989225341610930846E1,
- 1.79368678507819816313E1,
- 7.70838733755885391666E0,
-};
-static double Q[] = {
-/* 1.00000000000000000000E0, */
- 1.12873587189167450590E1,
- 4.52279145837532221105E1,
- 8.29875266912776603211E1,
- 7.11544750618563894466E1,
- 2.31251620126765340583E1,
-};
-#endif
-
-#ifdef DEC
-static unsigned short P[] = {
-0037777,0127270,0162547,0057274,
-0041001,0054665,0164317,0005341,
-0041451,0034104,0031640,0105773,
-0041677,0011276,0123617,0160135,
-0041701,0126603,0053215,0117250,
-0041420,0115777,0135206,0030232,
-};
-static unsigned short Q[] = {
-/*0040200,0000000,0000000,0000000,*/
-0041220,0144332,0045272,0174241,
-0041742,0164566,0035720,0130431,
-0042246,0126327,0166065,0116357,
-0042372,0033420,0157525,0124560,
-0042271,0167002,0066537,0172303,
-0041730,0164777,0113711,0044407,
-};
-#endif
-
-#ifdef IBMPC
-static unsigned short P[] = {
-0x1bb0,0x93c3,0xb4c2,0x3f1a,
-0x52f2,0x3f56,0xd6f5,0x3fdf,
-0x6911,0xed92,0xd2ba,0x4012,
-0xeb2e,0xc63e,0xff72,0x402c,
-0xc84d,0x924b,0xefd6,0x4031,
-0xdcf8,0x7d7e,0xd563,0x401e,
-};
-static unsigned short Q[] = {
-/*0x0000,0x0000,0x0000,0x3ff0,*/
-0xef8e,0xae97,0x9320,0x4026,
-0xc033,0x4e19,0x9d2c,0x4046,
-0xbdbd,0xa326,0xbf33,0x4054,
-0xae21,0xeb5e,0xc9e2,0x4051,
-0x25b2,0x9e1f,0x200a,0x4037,
-};
-#endif
-
-#ifdef MIEEE
-static unsigned short P[] = {
-0x3f1a,0xb4c2,0x93c3,0x1bb0,
-0x3fdf,0xd6f5,0x3f56,0x52f2,
-0x4012,0xd2ba,0xed92,0x6911,
-0x402c,0xff72,0xc63e,0xeb2e,
-0x4031,0xefd6,0x924b,0xc84d,
-0x401e,0xd563,0x7d7e,0xdcf8,
-};
-static unsigned short Q[] = {
-/*0x3ff0,0x0000,0x0000,0x0000,*/
-0x4026,0x9320,0xae97,0xef8e,
-0x4046,0x9d2c,0x4e19,0xc033,
-0x4054,0xbf33,0xa326,0xbdbd,
-0x4051,0xc9e2,0xeb5e,0xae21,
-0x4037,0x200a,0x9e1f,0x25b2,
-};
-#endif
-
-/* Coefficients for log(x) = z + z**3 P(z)/Q(z),
- * where z = 2(x-1)/(x+1)
- * 1/sqrt(2) <= x < sqrt(2)
- */
-
-#ifdef UNK
-static double R[3] = {
--7.89580278884799154124E-1,
- 1.63866645699558079767E1,
--6.41409952958715622951E1,
-};
-static double S[3] = {
-/* 1.00000000000000000000E0,*/
--3.56722798256324312549E1,
- 3.12093766372244180303E2,
--7.69691943550460008604E2,
-};
-#endif
-#ifdef DEC
-static unsigned short R[12] = {
-0140112,0020756,0161540,0072035,
-0041203,0013743,0114023,0155527,
-0141600,0044060,0104421,0050400,
-};
-static unsigned short S[12] = {
-/*0040200,0000000,0000000,0000000,*/
-0141416,0130152,0017543,0064122,
-0042234,0006000,0104527,0020155,
-0142500,0066110,0146631,0174731,
-};
-#endif
-#ifdef IBMPC
-static unsigned short R[12] = {
-0x0e84,0xdc6c,0x443d,0xbfe9,
-0x7b6b,0x7302,0x62fc,0x4030,
-0x2a20,0x1122,0x0906,0xc050,
-};
-static unsigned short S[12] = {
-/*0x0000,0x0000,0x0000,0x3ff0,*/
-0x6d0a,0x43ec,0xd60d,0xc041,
-0xe40e,0x112a,0x8180,0x4073,
-0x3f3b,0x19b3,0x0d89,0xc088,
-};
-#endif
-#ifdef MIEEE
-static unsigned short R[12] = {
-0xbfe9,0x443d,0xdc6c,0x0e84,
-0x4030,0x62fc,0x7302,0x7b6b,
-0xc050,0x0906,0x1122,0x2a20,
-};
-static unsigned short S[12] = {
-/*0x3ff0,0x0000,0x0000,0x0000,*/
-0xc041,0xd60d,0x43ec,0x6d0a,
-0x4073,0x8180,0x112a,0xe40e,
-0xc088,0x0d89,0x19b3,0x3f3b,
-};
-#endif
-
-#ifdef ANSIPROT
-extern double frexp ( double, int * );
-extern double ldexp ( double, int );
-extern double polevl ( double, void *, int );
-extern double p1evl ( double, void *, int );
-extern int isnan ( double );
-extern int isfinite ( double );
-#else
-double frexp(), ldexp(), polevl(), p1evl();
-int isnan(), isfinite();
-#endif
-#define SQRTH 0.70710678118654752440
-extern double INFINITY, NAN;
-
-double log(x)
-double x;
-{
-int e;
-#ifdef DEC
-short *q;
-#endif
-double y, z;
-
-#ifdef NANS
-if( isnan(x) )
- return(x);
-#endif
-#ifdef INFINITIES
-if( x == INFINITY )
- return(x);
-#endif
-/* Test for domain */
-if( x <= 0.0 )
- {
- if( x == 0.0 )
- {
- mtherr( fname, SING );
- return( -INFINITY );
- }
- else
- {
- mtherr( fname, DOMAIN );
- return( NAN );
- }
- }
-
-/* separate mantissa from exponent */
-
-#ifdef DEC
-q = (short *)&x;
-e = *q; /* short containing exponent */
-e = ((e >> 7) & 0377) - 0200; /* the exponent */
-*q &= 0177; /* strip exponent from x */
-*q |= 040000; /* x now between 0.5 and 1 */
-#endif
-
-/* Note, frexp is used so that denormal numbers
- * will be handled properly.
- */
-#ifdef IBMPC
-x = frexp( x, &e );
-/*
-q = (short *)&x;
-q += 3;
-e = *q;
-e = ((e >> 4) & 0x0fff) - 0x3fe;
-*q &= 0x0f;
-*q |= 0x3fe0;
-*/
-#endif
-
-/* Equivalent C language standard library function: */
-#ifdef UNK
-x = frexp( x, &e );
-#endif
-
-#ifdef MIEEE
-x = frexp( x, &e );
-#endif
-
-
-
-/* logarithm using log(x) = z + z**3 P(z)/Q(z),
- * where z = 2(x-1)/x+1)
- */
-
-if( (e > 2) || (e < -2) )
-{
-if( x < SQRTH )
- { /* 2( 2x-1 )/( 2x+1 ) */
- e -= 1;
- z = x - 0.5;
- y = 0.5 * z + 0.5;
- }
-else
- { /* 2 (x-1)/(x+1) */
- z = x - 0.5;
- z -= 0.5;
- y = 0.5 * x + 0.5;
- }
-
-x = z / y;
-
-
-/* rational form */
-z = x*x;
-z = x * ( z * polevl( z, R, 2 ) / p1evl( z, S, 3 ) );
-y = e;
-z = z - y * 2.121944400546905827679e-4;
-z = z + x;
-z = z + e * 0.693359375;
-goto ldone;
-}
-
-
-
-/* logarithm using log(1+x) = x - .5x**2 + x**3 P(x)/Q(x) */
-
-if( x < SQRTH )
- {
- e -= 1;
- x = ldexp( x, 1 ) - 1.0; /* 2x - 1 */
- }
-else
- {
- x = x - 1.0;
- }
-
-
-/* rational form */
-z = x*x;
-#if DEC
-y = x * ( z * polevl( x, P, 5 ) / p1evl( x, Q, 6 ) );
-#else
-y = x * ( z * polevl( x, P, 5 ) / p1evl( x, Q, 5 ) );
-#endif
-if( e )
- y = y - e * 2.121944400546905827679e-4;
-y = y - ldexp( z, -1 ); /* y - 0.5 * z */
-z = x + y;
-if( e )
- z = z + e * 0.693359375;
-
-ldone:
-
-return( z );
-}