diff options
author | Eric Andersen <andersen@codepoet.org> | 2001-11-22 14:04:29 +0000 |
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committer | Eric Andersen <andersen@codepoet.org> | 2001-11-22 14:04:29 +0000 |
commit | 7ce331c01ce6eb7b3f5c715a38a24359da9c6ee2 (patch) | |
tree | 3a7e8476e868ae15f4da1b7ce26b2db6f434468c /libm/double/pow.c | |
parent | c117dd5fb183afb1a4790a6f6110d88704be6bf8 (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/pow.c')
-rw-r--r-- | libm/double/pow.c | 756 |
1 files changed, 0 insertions, 756 deletions
diff --git a/libm/double/pow.c b/libm/double/pow.c deleted file mode 100644 index 768ad1062..000000000 --- a/libm/double/pow.c +++ /dev/null @@ -1,756 +0,0 @@ -/* pow.c - * - * Power function - * - * - * - * SYNOPSIS: - * - * double x, y, z, pow(); - * - * z = pow( x, y ); - * - * - * - * DESCRIPTION: - * - * Computes x raised to the yth power. Analytically, - * - * x**y = exp( y log(x) ). - * - * Following Cody and Waite, this program uses a lookup table - * of 2**-i/16 and pseudo extended precision arithmetic to - * obtain an extra three bits of accuracy in both the logarithm - * and the exponential. - * - * - * - * ACCURACY: - * - * Relative error: - * arithmetic domain # trials peak rms - * IEEE -26,26 30000 4.2e-16 7.7e-17 - * DEC -26,26 60000 4.8e-17 9.1e-18 - * 1/26 < x < 26, with log(x) uniformly distributed. - * -26 < y < 26, y uniformly distributed. - * IEEE 0,8700 30000 1.5e-14 2.1e-15 - * 0.99 < x < 1.01, 0 < y < 8700, uniformly distributed. - * - * - * ERROR MESSAGES: - * - * message condition value returned - * pow overflow x**y > MAXNUM INFINITY - * pow underflow x**y < 1/MAXNUM 0.0 - * pow domain x<0 and y noninteger 0.0 - * - */ - -/* -Cephes Math Library Release 2.8: June, 2000 -Copyright 1984, 1995, 2000 by Stephen L. Moshier -*/ - - -#include <math.h> -static char fname[] = {"pow"}; - -#define SQRTH 0.70710678118654752440 - -#ifdef UNK -static double P[] = { - 4.97778295871696322025E-1, - 3.73336776063286838734E0, - 7.69994162726912503298E0, - 4.66651806774358464979E0 -}; -static double Q[] = { -/* 1.00000000000000000000E0, */ - 9.33340916416696166113E0, - 2.79999886606328401649E1, - 3.35994905342304405431E1, - 1.39995542032307539578E1 -}; -/* 2^(-i/16), IEEE precision */ -static double A[] = { - 1.00000000000000000000E0, - 9.57603280698573700036E-1, - 9.17004043204671215328E-1, - 8.78126080186649726755E-1, - 8.40896415253714502036E-1, - 8.05245165974627141736E-1, - 7.71105412703970372057E-1, - 7.38413072969749673113E-1, - 7.07106781186547572737E-1, - 6.77127773468446325644E-1, - 6.48419777325504820276E-1, - 6.20928906036742001007E-1, - 5.94603557501360513449E-1, - 5.69394317378345782288E-1, - 5.45253866332628844837E-1, - 5.22136891213706877402E-1, - 5.00000000000000000000E-1 -}; -static double B[] = { - 0.00000000000000000000E0, - 1.64155361212281360176E-17, - 4.09950501029074826006E-17, - 3.97491740484881042808E-17, --4.83364665672645672553E-17, - 1.26912513974441574796E-17, - 1.99100761573282305549E-17, --1.52339103990623557348E-17, - 0.00000000000000000000E0 -}; -static double R[] = { - 1.49664108433729301083E-5, - 1.54010762792771901396E-4, - 1.33335476964097721140E-3, - 9.61812908476554225149E-3, - 5.55041086645832347466E-2, - 2.40226506959099779976E-1, - 6.93147180559945308821E-1 -}; - -#define douba(k) A[k] -#define doubb(k) B[k] -#define MEXP 16383.0 -#ifdef DENORMAL -#define MNEXP -17183.0 -#else -#define MNEXP -16383.0 -#endif -#endif - -#ifdef DEC -static unsigned short P[] = { -0037776,0156313,0175332,0163602, -0040556,0167577,0052366,0174245, -0040766,0062753,0175707,0055564, -0040625,0052035,0131344,0155636, -}; -static unsigned short Q[] = { -/*0040200,0000000,0000000,0000000,*/ -0041025,0052644,0154404,0105155, -0041337,0177772,0007016,0047646, -0041406,0062740,0154273,0020020, -0041137,0177054,0106127,0044555, -}; -static unsigned short A[] = { -0040200,0000000,0000000,0000000, -0040165,0022575,0012444,0103314, -0040152,0140306,0163735,0022071, -0040140,0146336,0166052,0112341, -0040127,0042374,0145326,0116553, -0040116,0022214,0012437,0102201, -0040105,0063452,0010525,0003333, -0040075,0004243,0117530,0006067, -0040065,0002363,0031771,0157145, -0040055,0054076,0165102,0120513, -0040045,0177326,0124661,0050471, -0040036,0172462,0060221,0120422, -0040030,0033760,0050615,0134251, -0040021,0141723,0071653,0010703, -0040013,0112701,0161752,0105727, -0040005,0125303,0063714,0044173, -0040000,0000000,0000000,0000000 -}; -static unsigned short B[] = { -0000000,0000000,0000000,0000000, -0021473,0040265,0153315,0140671, -0121074,0062627,0042146,0176454, -0121413,0003524,0136332,0066212, -0121767,0046404,0166231,0012553, -0121257,0015024,0002357,0043574, -0021736,0106532,0043060,0056206, -0121310,0020334,0165705,0035326, -0000000,0000000,0000000,0000000 -}; - -static unsigned short R[] = { -0034173,0014076,0137624,0115771, -0035041,0076763,0003744,0111311, -0035656,0141766,0041127,0074351, -0036435,0112533,0073611,0116664, -0037143,0054106,0134040,0152223, -0037565,0176757,0176026,0025551, -0040061,0071027,0173721,0147572 -}; - -/* -static double R[] = { -0.14928852680595608186e-4, -0.15400290440989764601e-3, -0.13333541313585784703e-2, -0.96181290595172416964e-2, -0.55504108664085595326e-1, -0.24022650695909537056e0, -0.69314718055994529629e0 -}; -*/ -#define douba(k) (*(double *)&A[(k)<<2]) -#define doubb(k) (*(double *)&B[(k)<<2]) -#define MEXP 2031.0 -#define MNEXP -2031.0 -#endif - -#ifdef IBMPC -static unsigned short P[] = { -0x5cf0,0x7f5b,0xdb99,0x3fdf, -0xdf15,0xea9e,0xddef,0x400d, -0xeb6f,0x7f78,0xccbd,0x401e, -0x9b74,0xb65c,0xaa83,0x4012, -}; -static unsigned short Q[] = { -/*0x0000,0x0000,0x0000,0x3ff0,*/ -0x914e,0x9b20,0xaab4,0x4022, -0xc9f5,0x41c1,0xffff,0x403b, -0x6402,0x1b17,0xccbc,0x4040, -0xe92e,0x918a,0xffc5,0x402b, -}; -static unsigned short A[] = { -0x0000,0x0000,0x0000,0x3ff0, -0x90da,0xa2a4,0xa4af,0x3fee, -0xa487,0xdcfb,0x5818,0x3fed, -0x529c,0xdd85,0x199b,0x3fec, -0xd3ad,0x995a,0xe89f,0x3fea, -0xf090,0x82a3,0xc491,0x3fe9, -0xa0db,0x422a,0xace5,0x3fe8, -0x0187,0x73eb,0xa114,0x3fe7, -0x3bcd,0x667f,0xa09e,0x3fe6, -0x5429,0xdd48,0xab07,0x3fe5, -0x2a27,0xd536,0xbfda,0x3fe4, -0x3422,0x4c12,0xdea6,0x3fe3, -0xb715,0x0a31,0x06fe,0x3fe3, -0x6238,0x6e75,0x387a,0x3fe2, -0x517b,0x3c7d,0x72b8,0x3fe1, -0x890f,0x6cf9,0xb558,0x3fe0, -0x0000,0x0000,0x0000,0x3fe0 -}; -static unsigned short B[] = { -0x0000,0x0000,0x0000,0x0000, -0x3707,0xd75b,0xed02,0x3c72, -0xcc81,0x345d,0xa1cd,0x3c87, -0x4b27,0x5686,0xe9f1,0x3c86, -0x6456,0x13b2,0xdd34,0xbc8b, -0x42e2,0xafec,0x4397,0x3c6d, -0x82e4,0xd231,0xf46a,0x3c76, -0x8a76,0xb9d7,0x9041,0xbc71, -0x0000,0x0000,0x0000,0x0000 -}; -static unsigned short R[] = { -0x937f,0xd7f2,0x6307,0x3eef, -0x9259,0x60fc,0x2fbe,0x3f24, -0xef1d,0xc84a,0xd87e,0x3f55, -0x33b7,0x6ef1,0xb2ab,0x3f83, -0x1a92,0xd704,0x6b08,0x3fac, -0xc56d,0xff82,0xbfbd,0x3fce, -0x39ef,0xfefa,0x2e42,0x3fe6 -}; - -#define douba(k) (*(double *)&A[(k)<<2]) -#define doubb(k) (*(double *)&B[(k)<<2]) -#define MEXP 16383.0 -#ifdef DENORMAL -#define MNEXP -17183.0 -#else -#define MNEXP -16383.0 -#endif -#endif - -#ifdef MIEEE -static unsigned short P[] = { -0x3fdf,0xdb99,0x7f5b,0x5cf0, -0x400d,0xddef,0xea9e,0xdf15, -0x401e,0xccbd,0x7f78,0xeb6f, -0x4012,0xaa83,0xb65c,0x9b74 -}; -static unsigned short Q[] = { -0x4022,0xaab4,0x9b20,0x914e, -0x403b,0xffff,0x41c1,0xc9f5, -0x4040,0xccbc,0x1b17,0x6402, -0x402b,0xffc5,0x918a,0xe92e -}; -static unsigned short A[] = { -0x3ff0,0x0000,0x0000,0x0000, -0x3fee,0xa4af,0xa2a4,0x90da, -0x3fed,0x5818,0xdcfb,0xa487, -0x3fec,0x199b,0xdd85,0x529c, -0x3fea,0xe89f,0x995a,0xd3ad, -0x3fe9,0xc491,0x82a3,0xf090, -0x3fe8,0xace5,0x422a,0xa0db, -0x3fe7,0xa114,0x73eb,0x0187, -0x3fe6,0xa09e,0x667f,0x3bcd, -0x3fe5,0xab07,0xdd48,0x5429, -0x3fe4,0xbfda,0xd536,0x2a27, -0x3fe3,0xdea6,0x4c12,0x3422, -0x3fe3,0x06fe,0x0a31,0xb715, -0x3fe2,0x387a,0x6e75,0x6238, -0x3fe1,0x72b8,0x3c7d,0x517b, -0x3fe0,0xb558,0x6cf9,0x890f, -0x3fe0,0x0000,0x0000,0x0000 -}; -static unsigned short B[] = { -0x0000,0x0000,0x0000,0x0000, -0x3c72,0xed02,0xd75b,0x3707, -0x3c87,0xa1cd,0x345d,0xcc81, -0x3c86,0xe9f1,0x5686,0x4b27, -0xbc8b,0xdd34,0x13b2,0x6456, -0x3c6d,0x4397,0xafec,0x42e2, -0x3c76,0xf46a,0xd231,0x82e4, -0xbc71,0x9041,0xb9d7,0x8a76, -0x0000,0x0000,0x0000,0x0000 -}; -static unsigned short R[] = { -0x3eef,0x6307,0xd7f2,0x937f, -0x3f24,0x2fbe,0x60fc,0x9259, -0x3f55,0xd87e,0xc84a,0xef1d, -0x3f83,0xb2ab,0x6ef1,0x33b7, -0x3fac,0x6b08,0xd704,0x1a92, -0x3fce,0xbfbd,0xff82,0xc56d, -0x3fe6,0x2e42,0xfefa,0x39ef -}; - -#define douba(k) (*(double *)&A[(k)<<2]) -#define doubb(k) (*(double *)&B[(k)<<2]) -#define MEXP 16383.0 -#ifdef DENORMAL -#define MNEXP -17183.0 -#else -#define MNEXP -16383.0 -#endif -#endif - -/* log2(e) - 1 */ -#define LOG2EA 0.44269504088896340736 - -#define F W -#define Fa Wa -#define Fb Wb -#define G W -#define Ga Wa -#define Gb u -#define H W -#define Ha Wb -#define Hb Wb - -#ifdef ANSIPROT -extern double floor ( double ); -extern double fabs ( double ); -extern double frexp ( double, int * ); -extern double ldexp ( double, int ); -extern double polevl ( double, void *, int ); -extern double p1evl ( double, void *, int ); -extern double powi ( double, int ); -extern int signbit ( double ); -extern int isnan ( double ); -extern int isfinite ( double ); -static double reduc ( double ); -#else -double floor(), fabs(), frexp(), ldexp(); -double polevl(), p1evl(), powi(); -int signbit(), isnan(), isfinite(); -static double reduc(); -#endif -extern double MAXNUM; -#ifdef INFINITIES -extern double INFINITY; -#endif -#ifdef NANS -extern double NAN; -#endif -#ifdef MINUSZERO -extern double NEGZERO; -#endif - -double pow( x, y ) -double x, y; -{ -double w, z, W, Wa, Wb, ya, yb, u; -/* double F, Fa, Fb, G, Ga, Gb, H, Ha, Hb */ -double aw, ay, wy; -int e, i, nflg, iyflg, yoddint; - -if( y == 0.0 ) - return( 1.0 ); -#ifdef NANS -if( isnan(x) ) - return( x ); -if( isnan(y) ) - return( y ); -#endif -if( y == 1.0 ) - return( x ); - - -#ifdef INFINITIES -if( !isfinite(y) && (x == 1.0 || x == -1.0) ) - { - mtherr( "pow", DOMAIN ); -#ifdef NANS - return( NAN ); -#else - return( INFINITY ); -#endif - } -#endif - -if( x == 1.0 ) - return( 1.0 ); - -if( y >= MAXNUM ) - { -#ifdef INFINITIES - if( x > 1.0 ) - return( INFINITY ); -#else - if( x > 1.0 ) - return( MAXNUM ); -#endif - if( x > 0.0 && x < 1.0 ) - return( 0.0); - if( x < -1.0 ) - { -#ifdef INFINITIES - return( INFINITY ); -#else - return( MAXNUM ); -#endif - } - if( x > -1.0 && x < 0.0 ) - return( 0.0 ); - } -if( y <= -MAXNUM ) - { - if( x > 1.0 ) - return( 0.0 ); -#ifdef INFINITIES - if( x > 0.0 && x < 1.0 ) - return( INFINITY ); -#else - if( x > 0.0 && x < 1.0 ) - return( MAXNUM ); -#endif - if( x < -1.0 ) - return( 0.0 ); -#ifdef INFINITIES - if( x > -1.0 && x < 0.0 ) - return( INFINITY ); -#else - if( x > -1.0 && x < 0.0 ) - return( MAXNUM ); -#endif - } -if( x >= MAXNUM ) - { -#if INFINITIES - if( y > 0.0 ) - return( INFINITY ); -#else - if( y > 0.0 ) - return( MAXNUM ); -#endif - return(0.0); - } -/* Set iyflg to 1 if y is an integer. */ -iyflg = 0; -w = floor(y); -if( w == y ) - iyflg = 1; - -/* Test for odd integer y. */ -yoddint = 0; -if( iyflg ) - { - ya = fabs(y); - ya = floor(0.5 * ya); - yb = 0.5 * fabs(w); - if( ya != yb ) - yoddint = 1; - } - -if( x <= -MAXNUM ) - { - if( y > 0.0 ) - { -#ifdef INFINITIES - if( yoddint ) - return( -INFINITY ); - return( INFINITY ); -#else - if( yoddint ) - return( -MAXNUM ); - return( MAXNUM ); -#endif - } - if( y < 0.0 ) - { -#ifdef MINUSZERO - if( yoddint ) - return( NEGZERO ); -#endif - return( 0.0 ); - } - } - -nflg = 0; /* flag = 1 if x<0 raised to integer power */ -if( x <= 0.0 ) - { - if( x == 0.0 ) - { - if( y < 0.0 ) - { -#ifdef MINUSZERO - if( signbit(x) && yoddint ) - return( -INFINITY ); -#endif -#ifdef INFINITIES - return( INFINITY ); -#else - return( MAXNUM ); -#endif - } - if( y > 0.0 ) - { -#ifdef MINUSZERO - if( signbit(x) && yoddint ) - return( NEGZERO ); -#endif - return( 0.0 ); - } - return( 1.0 ); - } - else - { - if( iyflg == 0 ) - { /* noninteger power of negative number */ - mtherr( fname, DOMAIN ); -#ifdef NANS - return(NAN); -#else - return(0.0L); -#endif - } - nflg = 1; - } - } - -/* Integer power of an integer. */ - -if( iyflg ) - { - i = w; - w = floor(x); - if( (w == x) && (fabs(y) < 32768.0) ) - { - w = powi( x, (int) y ); - return( w ); - } - } - -if( nflg ) - x = fabs(x); - -/* For results close to 1, use a series expansion. */ -w = x - 1.0; -aw = fabs(w); -ay = fabs(y); -wy = w * y; -ya = fabs(wy); -if((aw <= 1.0e-3 && ay <= 1.0) - || (ya <= 1.0e-3 && ay >= 1.0)) - { - z = (((((w*(y-5.)/720. + 1./120.)*w*(y-4.) + 1./24.)*w*(y-3.) - + 1./6.)*w*(y-2.) + 0.5)*w*(y-1.) )*wy + wy + 1.; - goto done; - } -/* These are probably too much trouble. */ -#if 0 -w = y * log(x); -if (aw > 1.0e-3 && fabs(w) < 1.0e-3) - { - z = (((((( - w/7. + 1.)*w/6. + 1.)*w/5. + 1.)*w/4. + 1.)*w/3. + 1.)*w/2. + 1.)*w + 1.; - goto done; - } - -if(ya <= 1.0e-3 && aw <= 1.0e-4) - { - z = ((((( - wy*1./720. - + (-w*1./48. + 1./120.) )*wy - + ((w*17./144. - 1./12.)*w + 1./24.) )*wy - + (((-w*5./16. + 7./24.)*w - 1./4.)*w + 1./6.) )*wy - + ((((w*137./360. - 5./12.)*w + 11./24.)*w - 1./2.)*w + 1./2.) )*wy - + (((((-w*1./6. + 1./5.)*w - 1./4)*w + 1./3.)*w -1./2.)*w ) )*wy - + wy + 1.0; - goto done; - } -#endif - -/* separate significand from exponent */ -x = frexp( x, &e ); - -#if 0 -/* For debugging, check for gross overflow. */ -if( (e * y) > (MEXP + 1024) ) - goto overflow; -#endif - -/* Find significand of x in antilog table A[]. */ -i = 1; -if( x <= douba(9) ) - i = 9; -if( x <= douba(i+4) ) - i += 4; -if( x <= douba(i+2) ) - i += 2; -if( x >= douba(1) ) - i = -1; -i += 1; - - -/* Find (x - A[i])/A[i] - * in order to compute log(x/A[i]): - * - * log(x) = log( a x/a ) = log(a) + log(x/a) - * - * log(x/a) = log(1+v), v = x/a - 1 = (x-a)/a - */ -x -= douba(i); -x -= doubb(i/2); -x /= douba(i); - - -/* rational approximation for log(1+v): - * - * log(1+v) = v - v**2/2 + v**3 P(v) / Q(v) - */ -z = x*x; -w = x * ( z * polevl( x, P, 3 ) / p1evl( x, Q, 4 ) ); -w = w - ldexp( z, -1 ); /* w - 0.5 * z */ - -/* Convert to base 2 logarithm: - * multiply by log2(e) - */ -w = w + LOG2EA * w; -/* Note x was not yet added in - * to above rational approximation, - * so do it now, while multiplying - * by log2(e). - */ -z = w + LOG2EA * x; -z = z + x; - -/* Compute exponent term of the base 2 logarithm. */ -w = -i; -w = ldexp( w, -4 ); /* divide by 16 */ -w += e; -/* Now base 2 log of x is w + z. */ - -/* Multiply base 2 log by y, in extended precision. */ - -/* separate y into large part ya - * and small part yb less than 1/16 - */ -ya = reduc(y); -yb = y - ya; - - -F = z * y + w * yb; -Fa = reduc(F); -Fb = F - Fa; - -G = Fa + w * ya; -Ga = reduc(G); -Gb = G - Ga; - -H = Fb + Gb; -Ha = reduc(H); -w = ldexp( Ga+Ha, 4 ); - -/* Test the power of 2 for overflow */ -if( w > MEXP ) - { -#ifndef INFINITIES - mtherr( fname, OVERFLOW ); -#endif -#ifdef INFINITIES - if( nflg && yoddint ) - return( -INFINITY ); - return( INFINITY ); -#else - if( nflg && yoddint ) - return( -MAXNUM ); - return( MAXNUM ); -#endif - } - -if( w < (MNEXP - 1) ) - { -#ifndef DENORMAL - mtherr( fname, UNDERFLOW ); -#endif -#ifdef MINUSZERO - if( nflg && yoddint ) - return( NEGZERO ); -#endif - return( 0.0 ); - } - -e = w; -Hb = H - Ha; - -if( Hb > 0.0 ) - { - e += 1; - Hb -= 0.0625; - } - -/* Now the product y * log2(x) = Hb + e/16.0. - * - * Compute base 2 exponential of Hb, - * where -0.0625 <= Hb <= 0. - */ -z = Hb * polevl( Hb, R, 6 ); /* z = 2**Hb - 1 */ - -/* Express e/16 as an integer plus a negative number of 16ths. - * Find lookup table entry for the fractional power of 2. - */ -if( e < 0 ) - i = 0; -else - i = 1; -i = e/16 + i; -e = 16*i - e; -w = douba( e ); -z = w + w * z; /* 2**-e * ( 1 + (2**Hb-1) ) */ -z = ldexp( z, i ); /* multiply by integer power of 2 */ - -done: - -/* Negate if odd integer power of negative number */ -if( nflg && yoddint ) - { -#ifdef MINUSZERO - if( z == 0.0 ) - z = NEGZERO; - else -#endif - z = -z; - } -return( z ); -} - - -/* Find a multiple of 1/16 that is within 1/16 of x. */ -static double reduc(x) -double x; -{ -double t; - -t = ldexp( x, 4 ); -t = floor( t ); -t = ldexp( t, -4 ); -return(t); -} |