数学算法

				Function GAMMLN(XX:real):real;
				const
				  STP=2.50662827465; HALF=0.5; ONE=1.0; FPF=5.5;
				var
				  X,TMP,SER:double;
				  J:integer;
				  COF:array[1..6] of double;
				begin
				  COF[1]:=76.18009173;      COF[2]:=-86.50532033;
				  COF[3]:=24.01409822;      COF[4]:=-1.231739516;
				  COF[5]:= 0.120858003e-2;  COF[6]:=-0.536382e-5;
				  X:=XX-ONE;
				  TMP:=X+FPF;
				  TMP:=(X+HALF)*Ln(TMP)-TMP;
				  SER:=ONE;
				  For J:=1 To 6 do
				  begin
				      X:=X+ONE;
				      SER:=SER+COF[J]/X
				  end;
				  GAMMLN:=TMP+Ln(STP*SER);
				end;