implementation
//PROGRAM D3R5
//Driver for routine MIDPNT
uses
  unit2;
  {$R *.DFM}
Function FUNC2(X:real):real;
begin
    FUNC2:= 1 / Sqrt(X);
end;

Function FINT2(X:real):real;
//Integral of FUNC
begin
    FINT2:= 2 * Sqrt(x);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  F:TextFile;   I:Integer;
  A,B,S:real;
const
  s1='%16.6f'; s2='###';s3='%9.6f';
  NMAX = 10;
begin
  A:=0;
  B:=1;
  //輸出計算結果到文件
  AssignFile(F, 'd:\delphi_shu\p3\d3r5.dat');
  Rewrite(F);
  Writeln(F, 'Integral of FUNC2 computed with MIDPNT');
  Writeln(F, 'Actual value of integral is: ',
                           format(s3,[(FINT2(B)-FINT2(A))]));
  Writeln(F, '    n     Approx. Integral');
  For I:= 1 To NMAX do
    begin
      MIDPNT(A,B,S,I);
      Writeln(F,'    ',FormatFloat(s2,I),Format(s1,[s]));
    end;
  CloseFile(F);
  //屏幕顯示計算結果
  memo1.Lines.LoadFromFile('d:\delphi_shu\p3\d3r5.dat');
end;