view release on metacpan or  search on metacpan

libmd/spence.c  view on Meta::CPAN

/*							spence.c
 *
 *	Dilogarithm
 *
 *
 *
 * SYNOPSIS:
 *
 * double x, y, spence();
 *
 * y = spence( x );
 *
 *
 *
 * DESCRIPTION:
 *
 * Computes the integral
 *
 *                    x
 *                    -
 *                   | | md_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 "mconf.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,