00001 #include "CommonTools/Statistics/src/GammaLn.h"
00002 #include <cmath>
00003
00004 float
00005 GammaLn( float z )
00006 {
00007 const static double coefficients[6] =
00008 { 76.18009172947146, -86.50532032941677, 24.01409824083091,
00009 -1.231739572450155, 0.1208650973866179e-2, -0.5395239384953e-5 };
00010
00011 double temp = z+5.5;
00012 temp -= (z+0.5)*log(temp);
00013 double y = z;
00014 double series = 1.000000000190015;
00015 for( int term = 0; term < 6; term++ )
00016 series += coefficients[term]/++y;
00017 return -temp + log(2.5066282746310005*series/z);
00018 }
1.5.4