CocoRoboDesktop/pdf1.js/node_modules/cephes/cephes/fac.c

/*							fac.c
 *
 *	Factorial function
 *
 *
 *
 * SYNOPSIS:
 *
 * double y, fac();
 * int i;
 *
 * y = fac( i );
 *
 *
 *
 * DESCRIPTION:
 *
 * Returns factorial of i  =  1 * 2 * 3 * ... * i.
 * fac(0) = 1.0.
 *
 * Due to machine arithmetic bounds the largest value of
 * i accepted is 33 in DEC arithmetic or 170 in IEEE
 * arithmetic.  Greater values, or negative ones,
 * produce an error message and return MAXNUM.
 *
 *
 *
 * ACCURACY:
 *
 * For i < 34 the values are simply tabulated, and have
 * full machine accuracy.  If i > 55, fac(i) = gamma(i+1);
 * see gamma.c.
 *
 *                      Relative error:
 * arithmetic   domain      peak
 *    IEEE      0, 170    1.4e-15
 *    DEC       0, 33      1.4e-17
 *
 */

/*
Cephes Math Library Release 2.8:  June, 2000
Copyright 1984, 1987, 2000 by Stephen L. Moshier
*/

#include "mconf.h"

/* Factorials of integers from 0 through 33 */
#ifdef UNK
static double factbl[] = {
    1.00000000000000000000E0,          1.00000000000000000000E0,
    2.00000000000000000000E0,          6.00000000000000000000E0,
    2.40000000000000000000E1,          1.20000000000000000000E2,
    7.20000000000000000000E2,          5.04000000000000000000E3,
    4.03200000000000000000E4,          3.62880000000000000000E5,
    3.62880000000000000000E6,          3.99168000000000000000E7,
    4.79001600000000000000E8,          6.22702080000000000000E9,
    8.71782912000000000000E10,         1.30767436800000000000E12,
    2.09227898880000000000E13,         3.55687428096000000000E14,
    6.40237370572800000000E15,         1.21645100408832000000E17,
    2.43290200817664000000E18,         5.10909421717094400000E19,
    1.12400072777760768000E21,         2.58520167388849766400E22,
    6.20448401733239439360E23,         1.55112100433309859840E25,
    4.03291461126605635584E26,         1.0888869450418352160768E28,
    3.04888344611713860501504E29,      8.841761993739701954543616E30,
    2.6525285981219105863630848E32,    8.22283865417792281772556288E33,
    2.6313083693369353016721801216E35, 8.68331761881188649551819440128E36};
#define MAXFAC 33
#endif

#ifdef DEC
static unsigned short factbl[] = {
    0040200, 0000000, 0000000, 0000000, 0040200, 0000000, 0000000, 0000000,
    0040400, 0000000, 0000000, 0000000, 0040700, 0000000, 0000000, 0000000,
    0041300, 0000000, 0000000, 0000000, 0041760, 0000000, 0000000, 0000000,
    0042464, 0000000, 0000000, 0000000, 0043235, 0100000, 0000000, 0000000,
    0044035, 0100000, 0000000, 0000000, 0044661, 0030000, 0000000, 0000000,
    0045535, 0076000, 0000000, 0000000, 0046430, 0042500, 0000000, 0000000,
    0047344, 0063740, 0000000, 0000000, 0050271, 0112146, 0000000, 0000000,
    0051242, 0060731, 0040000, 0000000, 0052230, 0035673, 0126000, 0000000,
    0053230, 0035673, 0126000, 0000000, 0054241, 0137567, 0063300, 0000000,
    0055265, 0173546, 0051630, 0000000, 0056330, 0012711, 0101504, 0100000,
    0057407, 0006635, 0171012, 0150000, 0060461, 0040737, 0046656, 0030400,
    0061563, 0135223, 0005317, 0101540, 0062657, 0027031, 0127705, 0023155,
    0064003, 0061223, 0041723, 0156322, 0065115, 0045006, 0014773, 0004410,
    0066246, 0146044, 0172433, 0173526, 0067414, 0136077, 0027317, 0114261,
    0070566, 0044556, 0110753, 0045465, 0071737, 0031214, 0032075, 0036050,
    0073121, 0037543, 0070371, 0064146, 0074312, 0132550, 0052561, 0116443,
    0075512, 0132550, 0052561, 0116443, 0076721, 0005423, 0114035, 0025014};
#define MAXFAC 33
#endif

#ifdef IBMPC
static unsigned short factbl[] = {
    0x0000, 0x0000, 0x0000, 0x3ff0, 0x0000, 0x0000, 0x0000, 0x3ff0, 0x0000,
    0x0000, 0x0000, 0x4000, 0x0000, 0x0000, 0x0000, 0x4018, 0x0000, 0x0000,
    0x0000, 0x4038, 0x0000, 0x0000, 0x0000, 0x405e, 0x0000, 0x0000, 0x8000,
    0x4086, 0x0000, 0x0000, 0xb000, 0x40b3, 0x0000, 0x0000, 0xb000, 0x40e3,
    0x0000, 0x0000, 0x2600, 0x4116, 0x0000, 0x0000, 0xaf80, 0x414b, 0x0000,
    0x0000, 0x08a8, 0x4183, 0x0000, 0x0000, 0x8cfc, 0x41bc, 0x0000, 0xc000,
    0x328c, 0x41f7, 0x0000, 0x2800, 0x4c3b, 0x4234, 0x0000, 0x7580, 0x0777,
    0x4273, 0x0000, 0x7580, 0x0777, 0x42b3, 0x0000, 0xecd8, 0x37ee, 0x42f4,
    0x0000, 0xca73, 0xbeec, 0x4336, 0x9000, 0x3068, 0x02b9, 0x437b, 0x5a00,
    0xbe41, 0xe1b3, 0x43c0, 0xc620, 0xe9b5, 0x283b, 0x4406, 0xf06c, 0x6159,
    0x7752, 0x444e, 0xa4ce, 0x35f8, 0xe5c3, 0x4495, 0x7b9a, 0x687a, 0x6c52,
    0x44e0, 0x6121, 0xc33f, 0xa940, 0x4529, 0x7eeb, 0x9ea3, 0xd984, 0x4574,
    0xf316, 0xe5d9, 0x9787, 0x45c1, 0x6967, 0xd23d, 0xc92d, 0x460e, 0xa785,
    0x8687, 0xe651, 0x465b, 0x2d0d, 0x6e1f, 0x27ec, 0x46aa, 0x33a4, 0x0aae,
    0x56ad, 0x46f9, 0x33a4, 0x0aae, 0x56ad, 0x4749, 0xa541, 0x7303, 0x2162,
    0x479a};
#define MAXFAC 170
#endif

#ifdef MIEEE
static unsigned short factbl[] = {
    0x3ff0, 0x0000, 0x0000, 0x0000, 0x3ff0, 0x0000, 0x0000, 0x0000, 0x4000,
    0x0000, 0x0000, 0x0000, 0x4018, 0x0000, 0x0000, 0x0000, 0x4038, 0x0000,
    0x0000, 0x0000, 0x405e, 0x0000, 0x0000, 0x0000, 0x4086, 0x8000, 0x0000,
    0x0000, 0x40b3, 0xb000, 0x0000, 0x0000, 0x40e3, 0xb000, 0x0000, 0x0000,
    0x4116, 0x2600, 0x0000, 0x0000, 0x414b, 0xaf80, 0x0000, 0x0000, 0x4183,
    0x08a8, 0x0000, 0x0000, 0x41bc, 0x8cfc, 0x0000, 0x0000, 0x41f7, 0x328c,
    0xc000, 0x0000, 0x4234, 0x4c3b, 0x2800, 0x0000, 0x4273, 0x0777, 0x7580,
    0x0000, 0x42b3, 0x0777, 0x7580, 0x0000, 0x42f4, 0x37ee, 0xecd8, 0x0000,
    0x4336, 0xbeec, 0xca73, 0x0000, 0x437b, 0x02b9, 0x3068, 0x9000, 0x43c0,
    0xe1b3, 0xbe41, 0x5a00, 0x4406, 0x283b, 0xe9b5, 0xc620, 0x444e, 0x7752,
    0x6159, 0xf06c, 0x4495, 0xe5c3, 0x35f8, 0xa4ce, 0x44e0, 0x6c52, 0x687a,
    0x7b9a, 0x4529, 0xa940, 0xc33f, 0x6121, 0x4574, 0xd984, 0x9ea3, 0x7eeb,
    0x45c1, 0x9787, 0xe5d9, 0xf316, 0x460e, 0xc92d, 0xd23d, 0x6967, 0x465b,
    0xe651, 0x8687, 0xa785, 0x46aa, 0x27ec, 0x6e1f, 0x2d0d, 0x46f9, 0x56ad,
    0x0aae, 0x33a4, 0x4749, 0x56ad, 0x0aae, 0x33a4, 0x479a, 0x2162, 0x7303,
    0xa541};
#define MAXFAC 170
#endif

#ifdef ANSIPROT
double gamma(double);
#else
double gamma();
#endif
extern double MAXNUM;

double fac(i) int i;
{
  double x, f, n;
  int j;

  if (i < 0) {
    mtherr("fac", SING);
    return (MAXNUM);
  }

  if (i > MAXFAC) {
    mtherr("fac", OVERFLOW);
    return (MAXNUM);
  }

  /* Get answer from table for small i. */
  if (i < 34) {
#ifdef UNK
    return (factbl[i]);
#else
    return (*(double *)(&factbl[4 * i]));
#endif
  }
  /* Use gamma function for large i. */
  if (i > 55) {
    x = i + 1;
    return (gamma(x));
  }
  /* Compute directly for intermediate i. */
  n = 34.0;
  f = 34.0;
  for (j = 35; j <= i; j++) {
    n += 1.0;
    f *= n;
  }
#ifdef UNK
  f *= factbl[33];
#else
  f *= *(double *)(&factbl[4 * 33]);
#endif
  return (f);
}