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.math.complex; 019 020 import org.apache.commons.math.MathRuntimeException; 021 022 /** 023 * Static implementations of common 024 * {@link org.apache.commons.math.complex.Complex} utilities functions. 025 * 026 * @version $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $ 027 */ 028 public class ComplexUtils { 029 030 /** 031 * Default constructor. 032 */ 033 private ComplexUtils() { 034 super(); 035 } 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 IllegalArgumentException if r is negative 060 * @since 1.1 061 */ 062 public static Complex polar2Complex(double r, double theta) { 063 if (r < 0) { 064 throw MathRuntimeException.createIllegalArgumentException( 065 "negative complex module {0}", r); 066 } 067 return new Complex(r * Math.cos(theta), r * Math.sin(theta)); 068 } 069 070 }