program Matrices;
{$APPTYPE CONSOLE}
uses
 SysUtils;
type
 TMatrixRow = Array of Double; {preferrable to Real}
 TMatrix = Array of TMatrixRow;

procedure MatrixExchangeRows(M: TMatrix; First, Second: Integer);
var
 Help: TMatrixRow;
begin
 if (First < 0) or (First > High(M)) or (Second < 0) or (Second > High(M)) then
  Exit; {or whatever you like.}
 {Only pointers are exchanged!}
 Help := M[First];
 M[First] := M[Second];
 M[Second] := Help;
end;

procedure MatrixWrite(M: TMatrix);
var
 Row, Col: Integer;
begin
 for Row := 0 to High(M) do
 begin
  for Col := 0 to High(M[Row]) do
  Write(M[Row, Col]:10:2);
  Writeln;
 end;
 Writeln;
end;
var
 Matrix: TMatrix;
 Row, Column: Integer;
begin
 Randomize;
 SetLength(Matrix, 4, 4);
 for Row := 0 to High(Matrix) do
  for Column := 0 to High(Matrix[Row]) do
  Matrix[Row, Column] := Random * 1000.0;
 MatrixWrite(Matrix);
 MatrixExchangeRows(Matrix, 1, 2);
 MatrixWrite(Matrix);
 Readln;
end.