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DDogleg Numerics is a high performance Java library for non-linear optimization, robust model fitting, polynomial root finding, sorting, and more.
/*
* Copyright (c) 2012-2017, Peter Abeles. All Rights Reserved.
*
* This file is part of DDogleg (http://ddogleg.org).
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.ddogleg.solver;
import org.ejml.data.DMatrixRMaj;
import org.ejml.dense.row.factory.LinearSolverFactory_DDRM;
import org.ejml.interfaces.linsol.LinearSolver;
/**
* Quadratic solver for an arbitrary 2D region
*
* @author Peter Abeles
*/
public class FitQuadratic2D {
LinearSolver solver = LinearSolverFactory_DDRM.leastSquares(10, 6);
DMatrixRMaj A = new DMatrixRMaj(1,6);
DMatrixRMaj b = new DMatrixRMaj(1,1);
DMatrixRMaj x = new DMatrixRMaj(6,1);
double foundX;
double foundY;
public void reset() {
A.reshape(0,6);
b.reshape(0,0);
}
public void add( double x , double y , double value ) {
int row = A.numRows;
// increase the size of A in larger steps for efficiency if needed
if( A.data.length < 6*row+6 ) {
int n = A.data.length*2;
A.reshape(n,1,true);
b.reshape(n/6,1,true);
}
A.reshape(row+1,6,true);
b.reshape(row+1,1,true);
A.set(row,0,x*x);
A.set(row,1,x*y);
A.set(row,2,y*y);
A.set(row,3,x);
A.set(row,4,y);
A.set(row,5,1);
b.set(row,value);
}
public boolean process() {
if( !solver.setA(A))
return false;
solver.solve(b,x);
double a = x.data[0];
double b = x.data[1];
double c = x.data[2];
double d = x.data[3];
double e = x.data[4];
double bottom = 4*a*c - b*b;
foundX = (b*e - 2*d*c)/bottom;
foundY = (b*d - 2*a*e)/bottom;
return true;
}
public double getFoundX() {
return foundX;
}
public double getFoundY() {
return foundY;
}
}