public double[][] getGridDydx1(){
            double[][] ret = new double[this.nPoints][this.mPoints];
            for(int i=0; i<this.nPoints; i++){
                for(int j=0; j<this.mPoints; j++){
                    ret[this.x1indices[i]][this.x2indices[j]] = this.dydx1[i][j];
                }
            }
            return ret;
        }