DEFINITION MODULE NRIMatr;

  (* EXPORT QUALIFIED IMatrix, PtrToILine, PtrToILines, NilIMatrix, EmptyIMatrix,
                      CreateIMatrix, DisposeIMatrix, DimensionsOfIMatrix,
                      IMatrixPtr, GetIMatrixAttr; *)

   CONST
      MaxNM = 1000;
   TYPE
      IMatrix;
      PtrToILine  = POINTER TO ARRAY [0..MaxNM-1] OF INTEGER;
      PtrToILines = POINTER TO ARRAY [0..MaxNM-1] OF PtrToILine;
   VAR
      NilIMatrix: IMatrix;


   PROCEDURE EmptyIMatrix(n, m: INTEGER): IMatrix;

      (* 
       * It creates a new integer matrix with line number n and column number m if
       * n, m > 0. Otherwise it returns NilIMatrix;
       * The elements in the matrix are undefined.
       *)

   PROCEDURE CreateIMatrix(    n, 
                               m: INTEGER;
                           VAR matrix: IMatrix;
                           VAR lines: PtrToILines);

      (* 
       * It creates a new matrix with n lines and m columns, if n, m > 0.  
       * It returns the reference variable "matrix" and a pointer to the lines
       * of the matrix. If n = 0 and m = 0, then matrix = NilIMatrix, lines = NIL.
       * The elements in the matrix are undefined.
       *)

   PROCEDURE DisposeIMatrix(VAR matrix: IMatrix);

      (*
       * The input "matrix" is deallocated. 
       * Output: "matrix"=NilImatrix;
       * Use this procedure only for matrices created before!
       *)

   PROCEDURE DimensionsOfIMatrix(    matrix: IMatrix;
                                 VAR n, m:   INTEGER);

      (* 
       * It returns the number lines and columns of matrix.
       *)

   PROCEDURE IMatrixPtr(matrix: IMatrix): PtrToILines;

      (* 
       * This procedure returns a pointer to the lines of matrix.
       *)

   PROCEDURE GetIMatrixAttr(    matrix: IMatrix;
                            VAR n, m:   INTEGER;
                            VAR lines:  PtrToILines);
      (* 
       * n, m: The number of lines and columns of matrix;
       * lines: Pointer to the lines of the matrix.
       *)


END NRIMatr.