MODULE Main;
IMPORT IO, Scan, Fmt, Text, FloatMode, Lex;

TYPE Matrix = REF ARRAY OF ARRAY OF REAL;

PROCEDURE Add(m1, m2 : Matrix) : Matrix =
  VAR
    rows := NUMBER(m1^);
    cols := NUMBER(m1[0]);
    res := NEW(Matrix, rows, cols);
  BEGIN
    IF NUMBER(m1^) # NUMBER(m2^) OR NUMBER(m1[0]) # NUMBER(m2[0]) THEN
      <* ASSERT FALSE *>
    END;
    FOR i := 0 TO rows - 1 DO
      FOR j := 0 TO cols - 1 DO
        res[i,j] := m1[i,j] + m2[i,j]
      END
    END;
    RETURN res
  END Add;

PROCEDURE Sub(m1, m2 : Matrix) : Matrix =
  VAR
    rows := NUMBER(m1^);
    cols := NUMBER(m1[0]);
    res := NEW(Matrix, rows, cols);
  BEGIN
    IF NUMBER(m1^) # NUMBER(m2^) OR NUMBER(m1[0]) # NUMBER(m2[0]) THEN
      <* ASSERT FALSE *>
    END;
    FOR i := 0 TO rows - 1 DO
      FOR j := 0 TO cols - 1 DO
        res[i,j] := m1[i,j] + m2[i,j]
      END
    END;
    RETURN res
  END Sub;

PROCEDURE Dump(m : Matrix) =
  BEGIN
    FOR i := FIRST(m^) TO LAST(m^) DO
      FOR j := FIRST(m[0]) TO LAST(m[0]) DO
        IO.Put("m("&Fmt.Int(i)&","&Fmt.Int(j)&") = " & Fmt.Real(m[i,j])&"\n")
      END
    END
  END Dump;

<* FATAL IO.Error, FloatMode.Trap, Lex.Error *>
VAR
  rows, cols : CARDINAL;
  m1, m2 : REF ARRAY OF ARRAY OF REAL;
  op : TEXT;
BEGIN
  IO.Put("Matrix 1 Rows?\n");
  rows := Scan.Int(IO.GetLine());
  IO.Put("Matrix 1 Columns?\n");
  cols := Scan.Int(IO.GetLine());

  m1 := NEW(REF ARRAY OF ARRAY OF REAL, rows, cols);

  FOR i := 0 TO rows - 1 DO
    FOR j := 0 TO cols - 1 DO
      IO.Put("m1(" & Fmt.Int(i) & "," & Fmt.Int(j) & ")?\n");
      m1[i,j] := Scan.Real(IO.GetLine())
    END
  END;

  IO.Put("Matrix 2 Rows?\n");
  rows := Scan.Int(IO.GetLine());
  IO.Put("Matrix 2 Columns?\n");
  cols := Scan.Int(IO.GetLine());

  m2 := NEW(REF ARRAY OF ARRAY OF REAL, rows, cols);

  FOR i := 0 TO rows - 1 DO
    FOR j := 0 TO cols - 1 DO
      IO.Put("m2(" & Fmt.Int(i) & "," & Fmt.Int(j) & ")?\n");
      m2[i,j] := Scan.Real(IO.GetLine())
    END
  END;
  
  IO.Put("Operation?\n");
  op := IO.GetLine();
  CASE Text.GetChar(op,0) OF
    '+' => Dump(Add(m1,m2))
  | 
    '-' => Dump(Sub(m1,m2))
  |
    '*' => 
  ELSE
    <* ASSERT FALSE *>
  END
END Main.