brent.dem

Delphi Pascal 数据挖掘领域算法包 数值算法大全

PROGRAM d10r3(input,output);
(* driver for routine BRENT *)
CONST
   tol=1.0e-6;
   eql=1.0e-4;
VAR
   ax,bx,cx,fa,fb,fc,xmin,bren : real;
   i,iflag,j,nmin : integer;
   amin : ARRAY [1..20] OF real;

(*$I MODFILE.PAS *)
(*$I BESSJ0.PAS *)

(*$I BESSJ1.PAS *)

FUNCTION func(x: real): real;
BEGIN
   func := bessj0(x)
END;

(*$I MNBRAK.PAS *)

(*$I BRENT.PAS *)

BEGIN
   nmin := 0;
   writeln;
   writeln('minima of the function bessj0');
   writeln('min. #':10,'x':8,'bessj0(x)':17,'bessj1(x)':12);
   FOR i := 1 to 100 DO BEGIN
      ax := i;
      bx := i+1.0;
      mnbrak(ax,bx,cx,fa,fb,fc);
      bren := brent(ax,bx,cx,tol,xmin);
      IF (nmin = 0) THEN BEGIN
         amin[1] := xmin;
         nmin := 1;
         writeln(nmin:7,xmin:15:6,bessj0(xmin):12:6,
            bessj1(xmin):12:6)
      END ELSE BEGIN
         iflag := 0;
         FOR j := 1 to nmin DO BEGIN
            IF  (abs(xmin-amin[j]) <= eql*xmin)
               THEN iflag := 1
         END;
         IF  (iflag = 0)  THEN BEGIN
            nmin := nmin+1;
            amin[nmin] := xmin;
            writeln(nmin:7,xmin:15:6,bessj0(xmin):12:6,
               bessj1(xmin):12:6)
         END
      END
   END
END.