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