DEFINITION MODULE NRLMatr;

  (* EXPORT QUALIFIED LMatrix, PtrToLLine, PtrToLLines, NilLMatrix, EmptyLMatrix,
                      CreateLMatrix, DisposeLMatrix, DimensionsOfLMatrix,
                      LMatrixPtr, GetLMatrixAttr, SetElement, GetElement; *)

   FROM NRSystem IMPORT LongReal;

   CONST
      MaxNM = 1000;
   TYPE
      LMatrix;
      PtrToLLine  = POINTER TO ARRAY [0..MaxNM-1] OF LongReal;
      PtrToLLines = POINTER TO ARRAY [0..MaxNM-1] OF PtrToLLine;
   VAR
      NilLMatrix: LMatrix;

   PROCEDURE EmptyLMatrix(n, m: INTEGER): LMatrix;

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

   PROCEDURE CreateLMatrix(    n, 
                               m: INTEGER;
                           VAR matrix: LMatrix;
                           VAR lines: PtrToLLines);
      (* 
       * 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 = NilLMatrix, lines = NIL.
       * The elements in the matrix are undefined.
       *)

   PROCEDURE DisposeLMatrix(VAR matrix: LMatrix);

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

   PROCEDURE DimensionsOfLMatrix(    matrix: LMatrix;
                                 VAR n, m:   INTEGER);

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

   PROCEDURE LMatrixPtr(matrix: LMatrix): PtrToLLines;

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

   PROCEDURE GetLMatrixAttr(    matrix: LMatrix;
                            VAR n, m:   INTEGER;
                            VAR lines:  PtrToLLines);
      (* 
       * n, m: The number of lines and columns of matrix;
       * lines: Pointer to the lines of the matrix.
       *)

   PROCEDURE SetElement(matrix: LMatrix;
                        i, j:   INTEGER;
                        number: LongReal);
      (* 
       * Sets the element with index i, j of the matrix to number.
       *)

   PROCEDURE GetElement(    matrix: LMatrix;
                            i, j:   INTEGER;
                        VAR number: LongReal);
      (* 
       * Gets the element with index i, j of the matrix in the variable number.
       *)

END NRLMatr.