ocssw: /disk01/web/ocssw/build/src/l2gen/gammln.c (r8218/r3324) Source File

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00001 #include <math.h>
00002 
00003 float gammln(float xx)
00004 {
00005     double x,y,tmp,ser;
00006     static double cof[6]={76.18009172947146,-86.50532032941677,
00007         24.01409824083091,-1.231739572450155,
00008         0.1208650973866179e-2,-0.5395239384953e-5};
00009     int j;
00010 
00011     y=x=xx;
00012     tmp=x+5.5;
00013     tmp -= (x+0.5)*log(tmp);
00014     ser=1.000000000190015;
00015     for (j=0;j<=5;j++) ser += cof[j]/++y;
00016     return -tmp+log(2.5066282746310005*ser/x);
00017 }