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 package org.apache.commons.math3.analysis.interpolation; 018 019 import org.apache.commons.math3.analysis.MultivariateFunction; 020 import org.apache.commons.math3.exception.NotPositiveException; 021 import org.apache.commons.math3.exception.NotStrictlyPositiveException; 022 import org.apache.commons.math3.exception.NoDataException; 023 import org.apache.commons.math3.exception.DimensionMismatchException; 024 import org.apache.commons.math3.exception.NullArgumentException; 025 import org.apache.commons.math3.random.UnitSphereRandomVectorGenerator; 026 027 /** 028 * Interpolator that implements the algorithm described in 029 * <em>William Dudziak</em>'s 030 * <a href="http://www.dudziak.com/microsphere.pdf">MS thesis</a>. 031 * 032 * @since 2.1 033 * @version $Id: MicrosphereInterpolator.java 1379904 2012-09-01 23:54:52Z erans $ 034 */ 035 public class MicrosphereInterpolator 036 implements MultivariateInterpolator { 037 /** 038 * Default number of surface elements that composes the microsphere. 039 */ 040 public static final int DEFAULT_MICROSPHERE_ELEMENTS = 2000; 041 /** 042 * Default exponent used the weights calculation. 043 */ 044 public static final int DEFAULT_BRIGHTNESS_EXPONENT = 2; 045 /** 046 * Number of surface elements of the microsphere. 047 */ 048 private final int microsphereElements; 049 /** 050 * Exponent used in the power law that computes the weights of the 051 * sample data. 052 */ 053 private final int brightnessExponent; 054 055 /** 056 * Create a microsphere interpolator with default settings. 057 * Calling this constructor is equivalent to call {@link 058 * #MicrosphereInterpolator(int, int) 059 * MicrosphereInterpolator(MicrosphereInterpolator.DEFAULT_MICROSPHERE_ELEMENTS, 060 * MicrosphereInterpolator.DEFAULT_BRIGHTNESS_EXPONENT)}. 061 */ 062 public MicrosphereInterpolator() { 063 this(DEFAULT_MICROSPHERE_ELEMENTS, DEFAULT_BRIGHTNESS_EXPONENT); 064 } 065 066 /** Create a microsphere interpolator. 067 * @param elements Number of surface elements of the microsphere. 068 * @param exponent Exponent used in the power law that computes the 069 * weights (distance dimming factor) of the sample data. 070 * @throws NotPositiveException if {@code exponent < 0}. 071 * @throws NotStrictlyPositiveException if {@code elements <= 0}. 072 */ 073 public MicrosphereInterpolator(final int elements, 074 final int exponent) 075 throws NotPositiveException, 076 NotStrictlyPositiveException { 077 if (exponent < 0) { 078 throw new NotPositiveException(exponent); 079 } 080 if (elements <= 0) { 081 throw new NotStrictlyPositiveException(elements); 082 } 083 084 microsphereElements = elements; 085 brightnessExponent = exponent; 086 } 087 088 /** 089 * {@inheritDoc} 090 */ 091 public MultivariateFunction interpolate(final double[][] xval, 092 final double[] yval) 093 throws DimensionMismatchException, 094 NoDataException, 095 NullArgumentException { 096 final UnitSphereRandomVectorGenerator rand 097 = new UnitSphereRandomVectorGenerator(xval[0].length); 098 return new MicrosphereInterpolatingFunction(xval, yval, 099 brightnessExponent, 100 microsphereElements, 101 rand); 102 } 103 }