Заполнить матрицу ЛП, от левого нижнего угла по диагонали: влево - вверх.
Пример 3*3
4   7   9
2   5   8
1   3   6

public interface Matrix
{
    /**
   * Return the number of rows in the matrix.
   * @return the number of rows in the matrix.
   */
  public int getNumberOfRows();

  /**
   * Return the number of columns in the matrix.
   * @return the number of columns in the matrix.
   */
  public int getNumberOfColumns();

  /**
   * Return element at position (row,column).
   *
   * @param row row of element to return.
   * @param column column of element to return.
   * @return element value of element.
   * @throws InvalidMatrixElementException if element position is not within
   * matrix.
   */
  public double getElement(final int row, final int column)
    throws InvalidMatrixElementException;

  /**
   * Set element at position (row,column). If the element is not within
   * the matrix, the matrix is left unchanged.
   *
   * @param row row of element to set.
   * @param column column of element to set.
   * @param value value to store at (row,column).
   * @throws InvalidMatrixElementException if element position is not within
   * matrix.
   */
  public void setElement(final int row, final int column, final double value)
    throws InvalidMatrixElementException;

  /**
   * Create a new concrete matrix of size (rows, columns). Must be
   * overridden by a subclass that names the actual class used
   * to create the matrix.
   *
   * @param rows number of rows in new matrix. Must be greater than zero.
   * @param columns number of columns in new matrix. Must be greater than zero.
   * @return the new matrix or null if the size is invalid.
   * @throws InvalidMatrixSizeException if size of matrix is not valid
   * (row/column lessthan size 1).
   */
  public Matrix create(final int rows, final int columns)
    throws InvalidMatrixSizeException;
}