001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.math3.complex;
019
020 import org.apache.commons.math3.exception.MathIllegalArgumentException;
021 import org.apache.commons.math3.exception.util.LocalizedFormats;
022 import org.apache.commons.math3.util.FastMath;
023
024 /**
025 * Static implementations of common
026 * {@link org.apache.commons.math3.complex.Complex} utilities functions.
027 *
028 * @version $Id: ComplexUtils.java 1416643 2012-12-03 19:37:14Z tn $
029 */
030 public class ComplexUtils {
031
032 /**
033 * Default constructor.
034 */
035 private ComplexUtils() {}
036
037 /**
038 * Creates a complex number from the given polar representation.
039 * <p>
040 * The value returned is <code>r·e<sup>i·theta</sup></code>,
041 * computed as <code>r·cos(theta) + r·sin(theta)i</code></p>
042 * <p>
043 * If either <code>r</code> or <code>theta</code> is NaN, or
044 * <code>theta</code> is infinite, {@link Complex#NaN} is returned.</p>
045 * <p>
046 * If <code>r</code> is infinite and <code>theta</code> is finite,
047 * infinite or NaN values may be returned in parts of the result, following
048 * the rules for double arithmetic.<pre>
049 * Examples:
050 * <code>
051 * polar2Complex(INFINITY, π/4) = INFINITY + INFINITY i
052 * polar2Complex(INFINITY, 0) = INFINITY + NaN i
053 * polar2Complex(INFINITY, -π/4) = INFINITY - INFINITY i
054 * polar2Complex(INFINITY, 5π/4) = -INFINITY - INFINITY i </code></pre></p>
055 *
056 * @param r the modulus of the complex number to create
057 * @param theta the argument of the complex number to create
058 * @return <code>r·e<sup>i·theta</sup></code>
059 * @throws MathIllegalArgumentException if {@code r} is negative.
060 * @since 1.1
061 */
062 public static Complex polar2Complex(double r, double theta) throws MathIllegalArgumentException {
063 if (r < 0) {
064 throw new MathIllegalArgumentException(
065 LocalizedFormats.NEGATIVE_COMPLEX_MODULE, r);
066 }
067 return new Complex(r * FastMath.cos(theta), r * FastMath.sin(theta));
068 }
069
070 /**
071 * Convert an array of primitive doubles to an array of {@code Complex} objects.
072 *
073 * @param real Array of numbers to be converted to their {@code Complex}
074 * equivalent.
075 * @return an array of {@code Complex} objects.
076 *
077 * @since 3.1
078 */
079 public static Complex[] convertToComplex(double[] real) {
080 final Complex c[] = new Complex[real.length];
081 for (int i = 0; i < real.length; i++) {
082 c[i] = new Complex(real[i], 0);
083 }
084
085 return c;
086 }
087 }