Re: [Repast-developer] Comment about DoubleMatrix and copyTo method.

[Mark R. D. <mdi...@la...>]

Is it really neccessary to reallocate memory everytime you use 
DoubleArray.copyTo? This seems to be expensive to me, especially in the 
case of Diffuse2D.


  /**
   * Copies the double[] in this DoubleMatrix to the specified DoubleMatrix.
   */
  public void copyMatrixTo(DoubleMatrix dm) {
    double[] aMatrix = new double[sizeY * sizeX];
    System.arraycopy(matrix, 0, aMatrix, 0, sizeY * sizeX);
    dm.matrix = aMatrix;
  }

I think the above method could easily be written as:

  public void copyMatrixTo(DoubleMatrix dm) {
    System.arraycopy(matrix, 0, dm.matrix , 0, sizeY * sizeX);
  }

without having to build a new double array. I understand that the matri 
could be different sizes so:

  /**
   * Copies the double[] in this DoubleMatrix to the specified DoubleMatrix.
   */
  public void copyMatrixTo(DoubleMatrix dm) {
    if(matix.length != dm.matrix.length){
       double[] aMatrix = new double[sizeY * sizeX];
       System.arraycopy(matrix, 0, aMatrix, 0, sizeY * sizeX);
       dm.matrix = aMatrix;
   }else{
      System.arraycopy(matrix, 0, dm.matrix , 0, sizeY * sizeX);
  }
}

captures that case while still providing efficient copying of 
DoubleArrays of equal sizes by reusing allocated memory.

what do you think?
Mark