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Java example source code file (ParameterJacobianWrapper.java)

This example Java source code file (ParameterJacobianWrapper.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

collection, dimensionmismatchexception, double, firstorderdifferentialequations, hashmap, maxcountexceededexception, parameterconfiguration, parameterizedode, parameterjacobianprovider, parameterjacobianwrapper, string, util

The ParameterJacobianWrapper.java Java example source code

/*
 * 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.math3.ode;

import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.math3.exception.DimensionMismatchException;
import org.apache.commons.math3.exception.MaxCountExceededException;

/** Wrapper class to compute Jacobian matrices by finite differences for ODE
 *  which do not compute them by themselves.
 *
 * @since 3.0
 */
class ParameterJacobianWrapper implements ParameterJacobianProvider {

    /** Main ODE set. */
    private final FirstOrderDifferentialEquations fode;

    /** Raw ODE without Jacobian computation skill to be wrapped into a ParameterJacobianProvider. */
    private final ParameterizedODE pode;

    /** Steps for finite difference computation of the Jacobian df/dp w.r.t. parameters. */
    private final Map<String, Double> hParam;

    /** Wrap a {@link ParameterizedODE} into a {@link ParameterJacobianProvider}.
     * @param fode main first order differential equations set
     * @param pode secondary problem, without parameter Jacobian computation skill
     * @param paramsAndSteps parameters and steps to compute the Jacobians df/dp
     * @see JacobianMatrices#setParameterStep(String, double)
     */
    ParameterJacobianWrapper(final FirstOrderDifferentialEquations fode,
                             final ParameterizedODE pode,
                             final ParameterConfiguration[] paramsAndSteps) {
        this.fode = fode;
        this.pode = pode;
        this.hParam = new HashMap<String, Double>();

        // set up parameters for jacobian computation
        for (final ParameterConfiguration param : paramsAndSteps) {
            final String name = param.getParameterName();
            if (pode.isSupported(name)) {
                hParam.put(name, param.getHP());
            }
        }
    }

    /** {@inheritDoc} */
    public Collection<String> getParametersNames() {
        return pode.getParametersNames();
    }

    /** {@inheritDoc} */
    public boolean isSupported(String name) {
        return pode.isSupported(name);
    }

    /** {@inheritDoc} */
    public void computeParameterJacobian(double t, double[] y, double[] yDot,
                                         String paramName, double[] dFdP)
        throws DimensionMismatchException, MaxCountExceededException {

        final int n = fode.getDimension();
        if (pode.isSupported(paramName)) {
            final double[] tmpDot = new double[n];

            // compute the jacobian df/dp w.r.t. parameter
            final double p  = pode.getParameter(paramName);
            final double hP = hParam.get(paramName);
            pode.setParameter(paramName, p + hP);
            fode.computeDerivatives(t, y, tmpDot);
            for (int i = 0; i < n; ++i) {
                dFdP[i] = (tmpDot[i] - yDot[i]) / hP;
            }
            pode.setParameter(paramName, p);
        } else {
            Arrays.fill(dFdP, 0, n, 0.0);
        }

    }

}

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