《Delphi常用数值算法集》的配书源码

				implementation
				//PROGRAM D3R9
				//Driver for routine GAULEG
				uses
				  unit2;
				  {$R *.DFM}
				
				Function FUNC(X:real):real;
				begin
				    FUNC:= X * Exp(-X);
				end;
				
				procedure TForm1.Button1Click(Sender: TObject);
				var
				  F:TextFile;   I,NPOINT:Integer;
				  X1,X2,X3,XX:real;
				  X,W:array[0..10] of real;
				const
				  s1='%14.6f'; s2='%10.6f'; s3='###';
				begin
				  NPOINT:=10;
				  X1:=0;
				  X2:=1;
				  X3:=10;
				  GAULEG(X1,X2,X,W,NPOINT);
				  //输出计算结果到文件
				  AssignFile(F, 'd:\delphi_shu\p3\d3r9.dat');
				  Rewrite(F);
				  Writeln(F, '  #         X(I)          W(I)');
				  For I:= 1 To NPOINT do
				    Writeln(F,'  ',FormatFloat(s3,I),Format(s1,[X[I]]),
				           Format(s1,[W[I]]));
				  //Demonstrate the use of GAULEG for an integral
				  GAULEG(X1,X3,X,W,NPOINT);
				  XX:=0;
				  For I:= 1 To NPOINT do
				    XX:= XX + W[I] * FUNC(X[I]);
				  Writeln(F);
				  Writeln(F,'Integral from GAULEG: ',Format(s2,[XX]));
				  Writeln(F,'Actual value: ',Format(s2,[1-(1+x3)*exp(-x3)]));
				
				  CloseFile(F);
				  //屏幕显示计算结果
				  memo1.Lines.LoadFromFile('d:\delphi_shu\p3\d3r9.dat');
				end;