gammln.dem

Delphi Pascal 数据挖掘领域算法包 数值算法大全

PROGRAM d6r1(input,output,dfile);
(* driver for routine GAMMLN *)
CONST
   pi = 3.1415926;
VAR
   i,nval : integer;
   actual,calc,x : real;
   txt : string[14];
   dfile : text;

(*$I MODFILE.PAS *)
(*$I GAMMLN.PAS *)

BEGIN
   glopen(dfile,'fncval.dat');
   REPEAT readln(dfile,txt) UNTIL (txt = 'Gamma Function');
   readln(dfile,nval);
   writeln ('log of gamma function:');
   writeln ('x':10,'actual':21,'gammln(x)':22);
   FOR i := 1 to nval DO BEGIN
      readln(dfile,x,actual);
      IF (x > 0.0) THEN BEGIN
         IF (x >= 1.0) THEN BEGIN
            calc := gammln(x)
         END ELSE BEGIN
            calc := gammln(x+1.0)-ln(x)
         END;
         writeln (x:12:2,ln(actual):20:6,calc:20:6)
      END
   END;
   close(dfile)
END.