implementation
//PROGRAM D3R2
//Driver for routine QTRAP
uses
  unit2;
  {$R *.DFM}
Function FUNC(X:real):real;
begin
    FUNC:= Sqr(X)*(Sqr(X) - 2) * Sin(X);
end;

Function FINT(X:real):real;
//Integral of FUNC
var
    AAA:real;
begin
    AAA:= 4 * X * (Sqr(x) - 7) * Sin(X);
    FINT:= AAA - (Sqr(Sqr(x)) - 14 * Sqr(x) + 28) * Cos(X);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  F:TextFile;
  A,B,S:real;
const
  s3='%9.6f';   PIO2=1.5707963;
begin
  A:=0;
  B:=PIO2;
  //輸出計算結果到文件
  AssignFile(F, 'd:\delphi_shu\p3\d3r2.dat');
  Rewrite(F);
  Writeln(F, 'Integral of FUNC computed with QTRAP is:');
  Writeln(F, 'Actual value of integral is: ',
                   format(s3,[(fint(b)-fint(a))]));
  QTRAP(A,B,S);
  Writeln(F, 'Result from routine QTRAP is: ',format(s3,[S]));
  CloseFile(F);
  //屏幕顯示計算結果
  memo1.Lines.LoadFromFile('d:\delphi_shu\p3\d3r2.dat');
end;