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Diffstat (limited to 'libm/double/spence.c')
| -rw-r--r-- | libm/double/spence.c | 205 |
1 files changed, 0 insertions, 205 deletions
diff --git a/libm/double/spence.c b/libm/double/spence.c deleted file mode 100644 index e2a56176b..000000000 --- a/libm/double/spence.c +++ /dev/null @@ -1,205 +0,0 @@ -/* spence.c - * - * Dilogarithm - * - * - * - * SYNOPSIS: - * - * double x, y, spence(); - * - * y = spence( x ); - * - * - * - * DESCRIPTION: - * - * Computes the integral - * - * x - * - - * | | log t - * spence(x) = - | ----- dt - * | | t - 1 - * - - * 1 - * - * for x >= 0. A rational approximation gives the integral in - * the interval (0.5, 1.5). Transformation formulas for 1/x - * and 1-x are employed outside the basic expansion range. - * - * - * - * ACCURACY: - * - * Relative error: - * arithmetic domain # trials peak rms - * IEEE 0,4 30000 3.9e-15 5.4e-16 - * DEC 0,4 3000 2.5e-16 4.5e-17 - * - * - */ - -/* spence.c */ - - -/* -Cephes Math Library Release 2.8: June, 2000 -Copyright 1985, 1987, 1989, 2000 by Stephen L. Moshier -*/ - -#include <math.h> - -#ifdef UNK -static double A[8] = { - 4.65128586073990045278E-5, - 7.31589045238094711071E-3, - 1.33847639578309018650E-1, - 8.79691311754530315341E-1, - 2.71149851196553469920E0, - 4.25697156008121755724E0, - 3.29771340985225106936E0, - 1.00000000000000000126E0, -}; -static double B[8] = { - 6.90990488912553276999E-4, - 2.54043763932544379113E-2, - 2.82974860602568089943E-1, - 1.41172597751831069617E0, - 3.63800533345137075418E0, - 5.03278880143316990390E0, - 3.54771340985225096217E0, - 9.99999999999999998740E-1, -}; -#endif -#ifdef DEC -static unsigned short A[32] = { -0034503,0013315,0034120,0157771, -0036357,0135043,0016766,0150637, -0037411,0007533,0005212,0161475, -0040141,0031563,0023217,0120331, -0040455,0104461,0007002,0155522, -0040610,0034434,0065721,0120465, -0040523,0006674,0105671,0054427, -0040200,0000000,0000000,0000000, -}; -static unsigned short B[32] = { -0035465,0021626,0032367,0144157, -0036720,0016326,0134431,0000406, -0037620,0161024,0133701,0120766, -0040264,0131557,0152055,0064512, -0040550,0152424,0051166,0034272, -0040641,0006233,0014672,0111572, -0040543,0006674,0105671,0054425, -0040200,0000000,0000000,0000000, -}; -#endif -#ifdef IBMPC -static unsigned short A[32] = { -0x1bff,0xa70a,0x62d9,0x3f08, -0xda34,0x63be,0xf744,0x3f7d, -0x5c68,0x6151,0x21eb,0x3fc1, -0xf41b,0x64d1,0x266e,0x3fec, -0x5b6a,0x21c0,0xb126,0x4005, -0x3427,0x8d7a,0x0723,0x4011, -0x2b23,0x9177,0x61b7,0x400a, -0x0000,0x0000,0x0000,0x3ff0, -}; -static unsigned short B[32] = { -0xf90e,0xc69e,0xa472,0x3f46, -0x2021,0xd723,0x039a,0x3f9a, -0x343f,0x96f8,0x1c42,0x3fd2, -0xad29,0xfa85,0x966d,0x3ff6, -0xc717,0x8a4e,0x1aa2,0x400d, -0x526f,0x6337,0x2193,0x4014, -0x2b23,0x9177,0x61b7,0x400c, -0x0000,0x0000,0x0000,0x3ff0, -}; -#endif -#ifdef MIEEE -static unsigned short A[32] = { -0x3f08,0x62d9,0xa70a,0x1bff, -0x3f7d,0xf744,0x63be,0xda34, -0x3fc1,0x21eb,0x6151,0x5c68, -0x3fec,0x266e,0x64d1,0xf41b, -0x4005,0xb126,0x21c0,0x5b6a, -0x4011,0x0723,0x8d7a,0x3427, -0x400a,0x61b7,0x9177,0x2b23, -0x3ff0,0x0000,0x0000,0x0000, -}; -static unsigned short B[32] = { -0x3f46,0xa472,0xc69e,0xf90e, -0x3f9a,0x039a,0xd723,0x2021, -0x3fd2,0x1c42,0x96f8,0x343f, -0x3ff6,0x966d,0xfa85,0xad29, -0x400d,0x1aa2,0x8a4e,0xc717, -0x4014,0x2193,0x6337,0x526f, -0x400c,0x61b7,0x9177,0x2b23, -0x3ff0,0x0000,0x0000,0x0000, -}; -#endif - -#ifdef ANSIPROT -extern double fabs ( double ); -extern double log ( double ); -extern double polevl ( double, void *, int ); -#else -double fabs(), log(), polevl(); -#endif -extern double PI, MACHEP; - -double spence(x) -double x; -{ -double w, y, z; -int flag; - -if( x < 0.0 ) - { - mtherr( "spence", DOMAIN ); - return(0.0); - } - -if( x == 1.0 ) - return( 0.0 ); - -if( x == 0.0 ) - return( PI*PI/6.0 ); - -flag = 0; - -if( x > 2.0 ) - { - x = 1.0/x; - flag |= 2; - } - -if( x > 1.5 ) - { - w = (1.0/x) - 1.0; - flag |= 2; - } - -else if( x < 0.5 ) - { - w = -x; - flag |= 1; - } - -else - w = x - 1.0; - - -y = -w * polevl( w, A, 7) / polevl( w, B, 7 ); - -if( flag & 1 ) - y = (PI * PI)/6.0 - log(x) * log(1.0-x) - y; - -if( flag & 2 ) - { - z = log(x); - y = -0.5 * z * z - y; - } - -return( y ); -} |