unit1.pas

《Delphi常用数值算法集》的配书源码

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation
//PROGRAM D2R2
//Driver for routine RATINT
uses
  unit2;
  {$R *.DFM}
Function FUNC(x:real):real;
begin
    FUNC:= X * Exp(-X)/(Sqr(X - 1)+1);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  X,Y:array[0..6] of real;
  XX,YY,DYY,YEXP:real;
  F:TextFile;  I:Integer;
const
  NPT=6; s1='%12.6f'; s2='.0000E+00'; s3='%6.2f';
begin
  For I:=1 to NPT do
  begin
      X[I]:= I * 2 / NPT;
      Y[I]:= FUNC(X[I]);
  end;
  //输出计算结果到文件
  AssignFile(F, 'd:\delphi_shu\p2\d2r2.dat');
  Rewrite(F);
  Writeln(F, 'Diagonal rationnal function interpolation');
  Writeln(F,'    X      interap.    accuracy     actual');
  For I:=1 To 10 do
  begin
      XX:= 0.2 * I;
      RATINT(X, Y, NPT, XX, YY, DYY);
      YEXP:= FUNC(XX);
      Writeln(F,Format(s3,[XX]),Format(s1,[YY]),'    ',
          FormatFloat(s2,DYY),Format(s1,[YEXP]));
  end;
  CloseFile(F);
  //屏幕显示计算结果
  memo1.ScrollBars:=ssVertical;
  memo1.Lines.LoadFromFile('d:\delphi_shu\p2\d2r2.dat');
end;

end.