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/*
* 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.analysis.interpolation;
import org.apache.commons.math.MathException;
import org.apache.commons.math.analysis.MultivariateRealFunction;
import org.apache.commons.math.exception.NotPositiveException;
import org.apache.commons.math.exception.NotStrictlyPositiveException;
import org.apache.commons.math.random.UnitSphereRandomVectorGenerator;
/**
* Interpolator that implements the algorithm described in
* <em>William Dudziak</em>'s
* <a href="http://www.dudziak.com/microsphere.pdf">MS thesis</a>.
* @since 2.1
*
* @version $Revision: 980944 $ $Date: 2010-07-30 22:31:11 +0200 (ven. 30 juil. 2010) $
*/
public class MicrosphereInterpolator
implements MultivariateRealInterpolator {
/**
* Default number of surface elements that composes the microsphere.
*/
public static final int DEFAULT_MICROSPHERE_ELEMENTS = 2000;
/**
* Default exponent used the weights calculation.
*/
public static final int DEFAULT_BRIGHTNESS_EXPONENT = 2;
/**
* Number of surface elements of the microsphere.
*/
private int microsphereElements;
/**
* Exponent used in the power law that computes the weights of the
* sample data.
*/
private int brightnessExponent;
/** Create a microsphere interpolator with default settings.
* <p>Calling this constructor is equivalent to call {@link
* #MicrosphereInterpolator(int, int)
* MicrosphereInterpolator(MicrosphereInterpolator.DEFAULT_MICROSPHERE_ELEMENTS,
* MicrosphereInterpolator.DEFAULT_BRIGHTNESS_EXPONENT)}.</p>
*/
public MicrosphereInterpolator() {
this(DEFAULT_MICROSPHERE_ELEMENTS, DEFAULT_BRIGHTNESS_EXPONENT);
}
/** Create a microsphere interpolator.
* @param microsphereElements number of surface elements of the microsphere.
* @param brightnessExponent exponent used in the power law that computes the
* weights of the sample data.
* @throws NotPositiveException if {@code microsphereElements <= 0}
* or {@code brightnessExponent < 0}.
*/
public MicrosphereInterpolator(final int microsphereElements,
final int brightnessExponent) {
setMicropshereElements(microsphereElements);
setBrightnessExponent(brightnessExponent);
}
/**
* {@inheritDoc}
*/
public MultivariateRealFunction interpolate(final double[][] xval,
final double[] yval)
throws MathException, IllegalArgumentException {
final UnitSphereRandomVectorGenerator rand
= new UnitSphereRandomVectorGenerator(xval[0].length);
return new MicrosphereInterpolatingFunction(xval, yval,
brightnessExponent,
microsphereElements,
rand);
}
/**
* Set the brightness exponent.
* @param exponent Exponent for computing the distance dimming
* factor.
* @throws NotPositiveException if {@code exponent < 0}.
*/
public void setBrightnessExponent(final int exponent) {
if (exponent < 0) {
throw new NotPositiveException(exponent);
}
brightnessExponent = exponent;
}
/**
* Set the number of microsphere elements.
* @param elements Number of surface elements of the microsphere.
* @throws NotStrictlyPositiveException if {@code elements <= 0}.
*/
public void setMicropshereElements(final int elements) {
if (elements <= 0) {
throw new NotStrictlyPositiveException(elements);
}
microsphereElements = elements;
}
}
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