georegression.struct.curve.ParabolaGeneral_F64 Maven / Gradle / Ivy

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GeoRegression is a free Java based geometry library for scientific computing in fields such as robotics and computer vision with a focus on 2D/3D space.
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/*
 * Copyright (C) 2022, Peter Abeles. All Rights Reserved.
 *
 * This file is part of Geometric Regression Library (GeoRegression).
 *
 * 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 georegression.struct.curve;

import org.ejml.UtilEjml;

/**
 * Parabola is a specific type of conic that is defined below using 5 coefficients.
 *
 * (A*x + C*y)² + D*x + E*y + F = 0
 *
 * @author Peter Abeles
 */
public class ParabolaGeneral_F64 {

	/**
	 * Coefficients.
	 */
	public double A, C, D, E, F;

	public ParabolaGeneral_F64( double a, double c, double d, double e, double f ) {
		A = a;
		C = c;
		D = d;
		E = e;
		F = f;
	}

	public ParabolaGeneral_F64( ParabolaGeneral_F64 original ) {
		this.setTo(original);
	}

	public ParabolaGeneral_F64() {}

	public ParabolaGeneral_F64 setTo( ParabolaGeneral_F64 original ) {
		this.A = original.A;
		this.C = original.C;
		this.D = original.D;
		this.E = original.E;
		this.F = original.F;
		return this;
	}

	public ParabolaGeneral_F64 setTo( double a, double c, double d, double e, double f ) {
		A = a;
		C = c;
		D = d;
		E = e;
		F = f;
		return this;
	}

	public void zero() {
		A = C = D = E = F = 0.0;
	}

	public double evaluate( double x, double y ) {
		double inner = A*x + C*y;
		return inner*inner + D*x + E*y + F;
	}

	public void toArray( double[] array ) {
		array[0] = A;
		array[1] = C;
		array[2] = D;
		array[3] = E;
		array[4] = F;
	}

	public void fromArray( double[] array ) {
		A = array[0];
		C = array[1];
		D = array[2];
		E = array[3];
		F = array[4];
	}

	/**
	 * Returns true if any of its parameters have an uncountable number
	 */
	public boolean hasUncountable() {
		return UtilEjml.isUncountable(A) || UtilEjml.isUncountable(C)
				|| UtilEjml.isUncountable(D) || UtilEjml.isUncountable(E) ||
				UtilEjml.isUncountable(F);
	}

	public double relativeScale( ParabolaGeneral_F64 parabola ) {
		double scale = A/parabola.A;
		double max = Math.abs(parabola.A);
		if (max < Math.abs(parabola.C)) {
			max = Math.abs(parabola.C);
			scale = C/parabola.C;
		}
		if (max < Math.abs(parabola.D)) {
			max = Math.abs(parabola.D);
			scale = D/parabola.D;
		}
		if (max < Math.abs(parabola.E)) {
			max = Math.abs(parabola.E);
			scale = E/parabola.E;
		}
		if (max < Math.abs(parabola.F)) {
			max = Math.abs(parabola.F);
			scale = F/parabola.F;
		}

		if (max == 0)
			scale = 0;
		return scale;
	}

	/**
	 * Determines if they are equivalent up to a scale factor
	 */
	public boolean isEquivalent( ParabolaGeneral_F64 parabola, double tol ) {
		double scale = relativeScale(parabola);

		if (Math.abs(A*scale - parabola.A) > tol)
			return false;
		if (Math.abs(C*scale - parabola.C) > tol)
			return false;
		if (Math.abs(D*scale - parabola.D) > tol)
			return false;
		if (Math.abs(E*scale - parabola.E) > tol)
			return false;
		if (Math.abs(F*scale - parabola.F) > tol)
			return false;

		return true;
	}
}