public double[] rowSums(){
            double[] sums = new double[this.numberOfRows];
            for(int i=0; i<this.numberOfRows; i++){
                sums[i] = 0.0;
                for(int j=0; j<this.numberOfColumns; j++){
                    sums[i] += this.matrix[i][j];
                }
            }
            return sums;
        }