/*******************************************************************************
* 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;
}
}