/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.commons.math.geometry.euclidean.twod;
import java.text.NumberFormat;
import org.apache.commons.math.exception.MathArithmeticException;
import org.apache.commons.math.exception.util.LocalizedFormats;
import org.apache.commons.math.geometry.Space;
import org.apache.commons.math.geometry.Vector;
import org.apache.commons.math.util.FastMath;
import org.apache.commons.math.util.MathUtils;
/** This class represents a 2D vector.
* <p>Instances of this class are guaranteed to be immutable.</p>
* @version $Id: Vector2D.java 1131152 2011-06-03 19:22:20Z luc $
* @since 3.0
*/
public class Vector2D implements Vector<Euclidean2D> {
/** Origin (coordinates: 0, 0). */
public static final Vector2D ZERO = new Vector2D(0, 0);
// CHECKSTYLE: stop ConstantName
/** A vector with all coordinates set to NaN. */
public static final Vector2D NaN = new Vector2D(Double.NaN, Double.NaN);
// CHECKSTYLE: resume ConstantName
/** A vector with all coordinates set to positive infinity. */
public static final Vector2D POSITIVE_INFINITY =
new Vector2D(Double.POSITIVE_INFINITY, Double.POSITIVE_INFINITY);
/** A vector with all coordinates set to negative infinity. */
public static final Vector2D NEGATIVE_INFINITY =
new Vector2D(Double.NEGATIVE_INFINITY, Double.NEGATIVE_INFINITY);
/** Serializable UID. */
private static final long serialVersionUID = 266938651998679754L;
/** Abscissa. */
private final double x;
/** Ordinate. */
private final double y;
/** Simple constructor.
* Build a vector from its coordinates
* @param x abscissa
* @param y ordinate
* @see #getX()
* @see #getY()
*/
public Vector2D(double x, double y) {
this.x = x;
this.y = y;
}
/** Multiplicative constructor
* Build a vector from another one and a scale factor.
* The vector built will be a * u
* @param a scale factor
* @param u base (unscaled) vector
*/
public Vector2D(double a, Vector2D u) {
this.x = a * u.x;
this.y = a * u.y;
}
/** Linear constructor
* Build a vector from two other ones and corresponding scale factors.
* The vector built will be a1 * u1 + a2 * u2
* @param a1 first scale factor
* @param u1 first base (unscaled) vector
* @param a2 second scale factor
* @param u2 second base (unscaled) vector
*/
public Vector2D(double a1, Vector2D u1, double a2, Vector2D u2) {
this.x = a1 * u1.x + a2 * u2.x;
this.y = a1 * u1.y + a2 * u2.y;
}
/** Linear constructor
* Build a vector from three other ones and corresponding scale factors.
* The vector built will be a1 * u1 + a2 * u2 + a3 * u3
* @param a1 first scale factor
* @param u1 first base (unscaled) vector
* @param a2 second scale factor
* @param u2 second base (unscaled) vector
* @param a3 third scale factor
* @param u3 third base (unscaled) vector
*/
public Vector2D(double a1, Vector2D u1, double a2, Vector2D u2,
double a3, Vector2D u3) {
this.x = a1 * u1.x + a2 * u2.x + a3 * u3.x;
this.y = a1 * u1.y + a2 * u2.y + a3 * u3.y;
}
/** Linear constructor
* Build a vector from four other ones and corresponding scale factors.
* The vector built will be a1 * u1 + a2 * u2 + a3 * u3 + a4 * u4
* @param a1 first scale factor
* @param u1 first base (unscaled) vector
* @param a2 second scale factor
* @param u2 second base (unscaled) vector
* @param a3 third scale factor
* @param u3 third base (unscaled) vector
* @param a4 fourth scale factor
* @param u4 fourth base (unscaled) vector
*/
public Vector2D(double a1, Vector2D u1, double a2, Vector2D u2,
double a3, Vector2D u3, double a4, Vector2D u4) {
this.x = a1 * u1.x + a2 * u2.x + a3 * u3.x + a4 * u4.x;
this.y = a1 * u1.y + a2 * u2.y + a3 * u3.y + a4 * u4.y;
}
/** Get the abscissa of the vector.
* @return abscissa of the vector
* @see #Vector2D(double, double)
*/
public double getX() {
return x;
}
/** Get the ordinate of the vector.
* @return ordinate of the vector
* @see #Vector2D(double, double)
*/
public double getY() {
return y;
}
/** {@inheritDoc} */
public Space getSpace() {
return Euclidean2D.getInstance();
}
/** {@inheritDoc} */
public Vector2D getZero() {
return ZERO;
}
/** {@inheritDoc} */
public double getNorm1() {
return FastMath.abs(x) + FastMath.abs(y);
}
/** {@inheritDoc} */
public double getNorm() {
return FastMath.sqrt (x * x + y * y);
}
/** {@inheritDoc} */
public double getNormSq() {
return x * x + y * y;
}
/** {@inheritDoc} */
public double getNormInf() {
return FastMath.max(FastMath.abs(x), FastMath.abs(y));
}
/** {@inheritDoc} */
public Vector2D add(Vector<Euclidean2D> v) {
Vector2D v2 = (Vector2D) v;
return new Vector2D(x + v2.getX(), y + v2.getY());
}
/** {@inheritDoc} */
public Vector2D add(double factor, Vector<Euclidean2D> v) {
Vector2D v2 = (Vector2D) v;
return new Vector2D(x + factor * v2.getX(), y + factor * v2.getY());
}
/** {@inheritDoc} */
public Vector2D subtract(Vector<Euclidean2D> p) {
Vector2D p3 = (Vector2D) p;
return new Vector2D(x - p3.x, y - p3.y);
}
/** {@inheritDoc} */
public Vector2D subtract(double factor, Vector<Euclidean2D> v) {
Vector2D v2 = (Vector2D) v;
return new Vector2D(x - factor * v2.getX(), y - factor * v2.getY());
}
/** {@inheritDoc} */
public Vector2D normalize() {
double s = getNorm();
if (s == 0) {
throw new MathArithmeticException(LocalizedFormats.CANNOT_NORMALIZE_A_ZERO_NORM_VECTOR);
}
return scalarMultiply(1 / s);
}
/** {@inheritDoc} */
public Vector2D negate() {
return new Vector2D(-x, -y);
}
/** {@inheritDoc} */
public Vector2D scalarMultiply(double a) {
return new Vector2D(a * x, a * y);
}
/** {@inheritDoc} */
public boolean isNaN() {
return Double.isNaN(x) || Double.isNaN(y);
}
/** {@inheritDoc} */
public boolean isInfinite() {
return !isNaN() && (Double.isInfinite(x) || Double.isInfinite(y));
}
/** {@inheritDoc} */
public double distance1(Vector<Euclidean2D> p) {
Vector2D p3 = (Vector2D) p;
final double dx = FastMath.abs(p3.x - x);
final double dy = FastMath.abs(p3.y - y);
return dx + dy;
}
/** {@inheritDoc} */
public double distance(Vector<Euclidean2D> p) {
Vector2D p3 = (Vector2D) p;
final double dx = p3.x - x;
final double dy = p3.y - y;
return FastMath.sqrt(dx * dx + dy * dy);
}
/** {@inheritDoc} */
public double distanceInf(Vector<Euclidean2D> p) {
Vector2D p3 = (Vector2D) p;
final double dx = FastMath.abs(p3.x - x);
final double dy = FastMath.abs(p3.y - y);
return FastMath.max(dx, dy);
}
/** {@inheritDoc} */
public double distanceSq(Vector<Euclidean2D> p) {
Vector2D p3 = (Vector2D) p;
final double dx = p3.x - x;
final double dy = p3.y - y;
return dx * dx + dy * dy;
}
/** {@inheritDoc} */
public double dotProduct(final Vector<Euclidean2D> v) {
final Vector2D v2 = (Vector2D) v;
return x * v2.x + y * v2.y;
}
/** Compute the distance between two vectors according to the L<sub>2</sub> norm.
* <p>Calling this method is equivalent to calling:
* <code>p1.subtract(p2).getNorm()</code> except that no intermediate
* vector is built</p>
* @param p1 first vector
* @param p2 second vector
* @return the distance between p1 and p2 according to the L<sub>2</sub> norm
*/
public static double distance(Vector2D p1, Vector2D p2) {
return p1.distance(p2);
}
/** Compute the distance between two vectors according to the L<sub>∞</sub> norm.
* <p>Calling this method is equivalent to calling:
* <code>p1.subtract(p2).getNormInf()</code> except that no intermediate
* vector is built</p>
* @param p1 first vector
* @param p2 second vector
* @return the distance between p1 and p2 according to the L<sub>∞</sub> norm
*/
public static double distanceInf(Vector2D p1, Vector2D p2) {
return p1.distanceInf(p2);
}
/** Compute the square of the distance between two vectors.
* <p>Calling this method is equivalent to calling:
* <code>p1.subtract(p2).getNormSq()</code> except that no intermediate
* vector is built</p>
* @param p1 first vector
* @param p2 second vector
* @return the square of the distance between p1 and p2
*/
public static double distanceSq(Vector2D p1, Vector2D p2) {
return p1.distanceSq(p2);
}
/**
* Test for the equality of two 2D vectors.
* <p>
* If all coordinates of two 2D vectors are exactly the same, and none are
* <code>Double.NaN</code>, the two 2D vectors are considered to be equal.
* </p>
* <p>
* <code>NaN</code> coordinates are considered to affect globally the vector
* and be equals to each other - i.e, if either (or all) coordinates of the
* 2D vector are equal to <code>Double.NaN</code>, the 2D vector is equal to
* {@link #NaN}.
* </p>
*
* @param other Object to test for equality to this
* @return true if two 2D vector objects are equal, false if
* object is null, not an instance of Vector2D, or
* not equal to this Vector2D instance
*
*/
@Override
public boolean equals(Object other) {
if (this == other) {
return true;
}
if (other instanceof Vector2D) {
final Vector2D rhs = (Vector2D)other;
if (rhs.isNaN()) {
return this.isNaN();
}
return (x == rhs.x) && (y == rhs.y);
}
return false;
}
/**
* Get a hashCode for the 2D vector.
* <p>
* All NaN values have the same hash code.</p>
*
* @return a hash code value for this object
*/
@Override
public int hashCode() {
if (isNaN()) {
return 542;
}
return 122 * (76 * MathUtils.hash(x) + MathUtils.hash(y));
}
/** Get a string representation of this vector.
* @return a string representation of this vector
*/
@Override
public String toString() {
return Vector2DFormat.getInstance().format(this);
}
/** {@inheritDoc} */
public String toString(final NumberFormat format) {
return new Vector2DFormat(format).format(this);
}
}