Move: ARRAY 4, 4 OF REAL =
  [[ 1,  0,  0,  0],
   [ 0,  1,  0,  0],
   [ 0,  0,  1,  0]
   [dx, dy, dz, 1]];

PROCEDURE  Set4f (OUT a: ARRAY OF GL.Float;  a0, a1, a2, a3: REAL);
BEGIN
   a[0] := SHORT(a0);  a[1] := SHORT(a1); 
   a[2] := SHORT(a2);  a[3] := SHORT(a3)
END Set4f;

move := e; move[3,0] := dx; ...

PROCEDURE RotateX(alpha: REAL): Matrix3d;
VAR
  m: Matrix3d;
BEGIN
  m[0, 0] := 1; m[0, 1] :=   0;                     m[0, 2] := 0;
  m[1, 0] := 0; m[1, 1] :=   Math.cos(alpha); m[1, 2] := Math.sin(alpha);
  m[2, 0] := 0; m[2, 1] :=  -Math.sin(alpha);  m[2, 2] := Math.cos(alpha);
  RETURN m
END RotateX;

MODULE Matrices; (** AUTHOR ""; PURPOSE ""; *)

IMPORT
   Math;
   
TYPE
   Matrix3d* = ARRAY 3, 3 OF REAL;
   
VAR
   Identity-: Matrix3d;
   RotateX5-: Matrix3d;
   
PROCEDURE RotateX*(alpha: REAL): Matrix3d;
VAR
  m: Matrix3d;
BEGIN
   m := Identity;
   m[1, 1] :=   Math.cos(alpha); m[1, 2] := Math.sin(alpha);
   m[2, 1] :=  -Math.sin(alpha);  m[2, 2] := Math.cos(alpha);
   RETURN m
END RotateX;

PROCEDURE Init;
VAR
   i, j: SHORTINT;
BEGIN
   (* Identity matrix init *)
   FOR j := 0 TO 2 DO
      FOR i := 0 TO 2 DO
         IF i = j THEN
            Identity[i, j] := 1
         ELSE
            Identity[i, j] := 0
         END
      END
   END;
   RotateX5 := RotateX(5 * Math.pi / 180)
END Init;

BEGIN
   Init;
END Matrices.

PROCEDURE Init;
VAR
   i, k: SHORTINT;
BEGIN
   (* Identity matrix init *)
   ASSERT(LEN(Identity) = LEN(Identity[0]), 20); (* square matrix *)
   Identity[0, 0] := 1;
   FOR i := 1 TO LEN(Identity) - 1 DO
      FOR k := 0 TO i - 1 DO (* from side to (but excluding) diagonal *)
         Identity[i, k] := 0; (* fill with zeroes *)
         Identity[k, i] := 0 (* from both sides *)
      END
      Identity[i, i] := 1 (* put diagonal element *)
   END
END Init;

 s[0]:='H';  s[1]:='e';  s[2]:='l';  s[3]:='l';  s[4]:='o';  s[5]:=' ';
 s[6]:='w';  s[7]:='o';  s[8]:='r';  s[9]:='l';  s[10]:='d';  s[11]:='!';
 s[12]:=0X;

UNIT Matrix;
INTERFACE
TYPE
  Matrix3d = ARRAY [0..3, 0..3] OF REAL;
CONST
  Ident: Matrix3d =
 ((1, 0, 0, 0),
  (0, 1, 0, 0),
  (0, 0, 1, 0),
  (0, 0, 0, 1));
IMPLEMENTATION
END.

MODULE Matix;
TYPE
  Matrix3d* = ARRAY 4, 4 OF REAL;
VAR
  Ident-: Matix3d;
  i, j: INTEGER;
BEGIN
  FOR i:=0 TO 3 DO
    FOR j:=0 TO 3 DO
      IF i = j THEN
        Ident[i, j] := 1;
      ELSE
        Ident[i, j] := 0
      END
    END
  END
END Matrix.

(* Identity matrix
  | 1  0  0  0 |
  | 0  1  0  0 |
  | 0  0  1  0 |
  | 0  0  0  1 |
*)

MODULE Matix;
TYPE  Matrix3d* = ARRAY 4, 4 OF REAL;
VAR
  Ident-: Matix3d;
  i, j: INTEGER;
BEGIN
  FOR i:=0 TO 3 DO
    FOR j:=0 TO 3 DO
      Ident[i, j] := 0
    END
  END;
  FOR i:=0 TO 3 DO
    Ident[i, i] := 1
  END
END Matrix.