| /* |
| * 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.geometry.euclidean.internal; |
| |
| import org.apache.commons.geometry.core.Vector; |
| |
| /** This class consists exclusively of static vector utility methods. |
| */ |
| public final class Vectors { |
| |
| /** Private constructor. */ |
| private Vectors() {} |
| |
| /** Returns true if the given value is real (ie, not NaN or inifinite) |
| * and not equal to zero. |
| * @param value the value to test |
| * @return true if {@code value} is not NaN, infinite, or zero; otherwise |
| * false |
| */ |
| public static boolean isRealNonZero(final double value) { |
| return Double.isFinite(value) && value != 0.0; |
| } |
| |
| /** Throws an {@link IllegalArgumentException} if the given norm value |
| * is not real (ie, not NaN or infinite) or zero. The argument is returned |
| * to allow this method to be called inline. |
| * @param norm vector norm value |
| * @return the validated norm value |
| * @throws IllegalArgumentException if the given norm value is NaN, infinite, |
| * or zero |
| */ |
| public static double checkedNorm(final double norm) { |
| if (!isRealNonZero(norm)) { |
| throw new IllegalArgumentException("Illegal norm: " + norm); |
| } |
| |
| return norm; |
| } |
| |
| /** Returns the vector's norm value, throwing an {@link IllegalArgumentException} if the value |
| * is not real (ie, not NaN or infinite) or zero. |
| * @param vec vector to obtain the real, non-zero norm of |
| * @return the validated norm value |
| * @throws IllegalArgumentException if the vector norm value is NaN, infinite, |
| * or zero |
| */ |
| public static double checkedNorm(final Vector<?> vec) { |
| return checkedNorm(vec.norm()); |
| } |
| |
| /** Attempt to normalize the given vector, returning null if the vector cannot be normalized |
| * due to the norm being NaN, infinite, or null. |
| * @param <V> Vector implementation type |
| * @param vec the vector to attempt to normalize |
| * @return the normalized vector if successful, otherwise null |
| */ |
| public static <V extends Vector<V>> V tryNormalize(final V vec) { |
| final double norm = vec.norm(); |
| if (isRealNonZero(norm)) { |
| return vec.normalize(); |
| } |
| return null; |
| } |
| |
| /** Get the L<sub>2</sub> norm (commonly known as the Euclidean norm) for the vector |
| * with the given components. This corresponds to the common notion of vector magnitude |
| * or length and is defined as the square root of the sum of the squares of all vector components. |
| * @param x vector component |
| * @return L<sub>2</sub> norm for the vector with the given components |
| * @see <a href="http://mathworld.wolfram.com/L2-Norm.html">L2 Norm</a> |
| */ |
| public static double norm(final double x) { |
| return Math.abs(x); |
| } |
| |
| /** Get the L<sub>2</sub> norm (commonly known as the Euclidean norm) for the vector |
| * with the given components. This corresponds to the common notion of vector magnitude |
| * or length and is defined as the square root of the sum of the squares of all vector components. |
| * @param x1 first vector component |
| * @param x2 second vector component |
| * @return L<sub>2</sub> norm for the vector with the given components |
| * @see <a href="http://mathworld.wolfram.com/L2-Norm.html">L2 Norm</a> |
| */ |
| public static double norm(final double x1, final double x2) { |
| return Math.hypot(x1, x2); |
| } |
| |
| /** Get the L<sub>2</sub> norm (commonly known as the Euclidean norm) for the vector |
| * with the given components. This corresponds to the common notion of vector magnitude |
| * or length and is defined as the square root of the sum of the squares of all vector components. |
| * @param x1 first vector component |
| * @param x2 second vector component |
| * @param x3 third vector component |
| * @return L<sub>2</sub> norm for the vector with the given components |
| * @see <a href="http://mathworld.wolfram.com/L2-Norm.html">L2 Norm</a> |
| */ |
| public static double norm(final double x1, final double x2, final double x3) { |
| return Math.sqrt(normSq(x1, x2, x3)); |
| } |
| |
| /** Get the square of the L<sub>2</sub> norm (also known as the Euclidean norm) |
| * for the vector with the given components. This is equal to the sum of the squares of |
| * all vector components. |
| * @param x vector component |
| * @return square of the L<sub>2</sub> norm for the vector with the given components |
| * @see #norm(double) |
| */ |
| public static double normSq(final double x) { |
| return x * x; |
| } |
| |
| /** Get the square of the L<sub>2</sub> norm (also known as the Euclidean norm) |
| * for the vector with the given components. This is equal to the sum of the squares of |
| * all vector components. |
| * @param x1 first vector component |
| * @param x2 second vector component |
| * @return square of the L<sub>2</sub> norm for the vector with the given components |
| * @see #norm(double, double) |
| */ |
| public static double normSq(final double x1, final double x2) { |
| return (x1 * x1) + (x2 * x2); |
| } |
| |
| /** Get the square of the L<sub>2</sub> norm (also known as the Euclidean norm) |
| * for the vector with the given components. This is equal to the sum of the squares of |
| * all vector components. |
| * @param x1 first vector component |
| * @param x2 second vector component |
| * @param x3 third vector component |
| * @return square of the L<sub>2</sub> norm for the vector with the given components |
| * @see #norm(double, double, double) |
| */ |
| public static double normSq(final double x1, final double x2, final double x3) { |
| return (x1 * x1) + (x2 * x2) + (x3 * x3); |
| } |
| } |