com.analog.lyric.dimple.solvers.sumproduct.customFactors.CustomGaussianProduct.java Source code

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Here is the source code for com.analog.lyric.dimple.solvers.sumproduct.customFactors.CustomGaussianProduct.java

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/*******************************************************************************
*   Copyright 2012 Analog Devices, Inc.
*
*   Licensed 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 com.analog.lyric.dimple.solvers.sumproduct.customFactors;

import com.analog.lyric.dimple.model.factors.Factor;
import com.analog.lyric.dimple.model.variables.VariablePredicates;
import com.analog.lyric.dimple.solvers.core.SolverFactorCreationException;
import com.analog.lyric.dimple.solvers.core.parameterizedMessages.NormalParameters;
import com.analog.lyric.dimple.solvers.sumproduct.SumProductSolverGraph;
import com.google.common.collect.Iterables;

public class CustomGaussianProduct extends GaussianFactorBase {

    private double _constant;
    private final static int PRODUCT_INDEX = 0;
    private final static int MULTIPLICAND_INDEX = 1;

    public CustomGaussianProduct(Factor factor, SumProductSolverGraph parent) {
        super(factor, parent);

        // Make sure this is of the form a = b*c where either b or c is a non-zero constant.
        if (factor.getSiblingCount() != 2)
            throw new SolverFactorCreationException("Factor must be of form a = b*c where b or c is a constant");

        if (factor.getConstantCount() != 1)
            throw new SolverFactorCreationException("Expected one constant");
        _constant = factor.getConstantValues().get(0).getDouble();
        if (_constant == 0)
            throw new SolverFactorCreationException("Constant of 0 not supported");

        assertUnboundedReal(factor);
    }

    @Override
    public void doUpdateEdge(int outPortNum) {
        if (outPortNum == PRODUCT_INDEX)
            updateProduct();
        else
            updateMultiplicand();
    }

    private void updateProduct() {
        NormalParameters outMsg = getSiblingEdgeState(PRODUCT_INDEX).factorToVarMsg;
        NormalParameters inMsg = getSiblingEdgeState(MULTIPLICAND_INDEX).varToFactorMsg;

        // Up = C*Uv
        outMsg.setMean(inMsg.getMean() * _constant);

        // SigmaP = C*sigmav
        outMsg.setStandardDeviation(inMsg.getStandardDeviation() * _constant);
    }

    private void updateMultiplicand() {
        NormalParameters outMsg = getSiblingEdgeState(MULTIPLICAND_INDEX).factorToVarMsg;
        NormalParameters inMsg = getSiblingEdgeState(PRODUCT_INDEX).varToFactorMsg;

        // Uv = Up/C
        outMsg.setMean(inMsg.getMean() / _constant);

        // Sigmav = sigmaP/c
        outMsg.setStandardDeviation(inMsg.getStandardDeviation() / Math.abs(_constant));
    }

    /**
     * Utility to indicate whether or not a factor is compatible with the requirements of this custom factor
     * @deprecated as of release 0.08
     */
    @Deprecated
    public static boolean isFactorCompatible(Factor factor) {
        // Must be of the form form a = b*c where either b or c is a constant.
        if (factor.getSiblingCount() != 2)
            return false;

        // Must have exactly one constant
        if (factor.getConstantCount() != 1)
            return false;

        // Variables must be real and univariate
        if (!Iterables.all(factor.getSiblings(), VariablePredicates.isUnboundedReal()))
            return false;

        // Constant must be non-zero
        double constant = factor.getConstantValues().get(0).getDouble();
        if (constant == 0)
            return false;

        return true;
    }

}