class Arrays2d {




    public static void initializeOneCell( double[][] data, int rowNum, int colNum ) {
      data[rowNum][colNum] = rowNum*colNum;
    }


   public static void initializeOneRow( double[][] data, int rowNum ) {
     for (int c=0;  c < data[rowNum].length;  ++c) {
       initializeOneCell(data, rowNum, c);
     }
   }

   public static void initializeArray( double[][] data ) {
     for (int r=0;  r < data.length;  ++r) {
       initializeOneRow(data, r);
     }
   }


    public static void main( String[] args ) {
        double[][] elevations = new double[4][7];

        initializeArray( elevations );


        System.out.println( "The array is: " + java.util.Arrays.deepToString( elevations ) );

    }
 
   /** Calculate the sum of one row of a 2-d array, given the desired row-number.
    * @param nums The 2-d array of numbers to add.
    * @param rowNum the desired row to add each column-value of.
    *    We must have 0 <= rowNum < nums.length.
    * @return  nums[rowNum][0]+nums[rowNum][1]+...
    */
   public static double sumOfRow( double[][] nums, int rowNum ) {
     double rowSumSoFar = 0.0;
     for (int c=0;  c < nums[rowNum].length;  ++c) {
        rowSumSoFar += nums[rowNum][c];
        }
     return rowSumSoFar;
     }
     
     
   /** Calculate the average value of a 2-d array.
    * @param nums The 2-d array of numbers to average.
    *    It must be non-empty.
    * @return The average (mean) of all numbers in `nums`.
    */
   public static double avg( double[][] nums ) {
     double sumSoFar = 0;
     for (int i=0;  i < nums.length;  ++i) {
       sumSoFar = sumOfRow( nums, i );
     }
     return sumSoFar / (nums.length * nums[0].length);
   }
    
    
    
}