/*******************************************************************************
* 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.factorfunctions;
import com.analog.lyric.dimple.factorfunctions.core.FactorFunction;
import com.analog.lyric.dimple.model.values.Value;
/**
* Deterministic complex product. This is a deterministic directed factor (if smoothing is
* not enabled).
*
* Optional smoothing may be applied, by providing a smoothing value in the
* constructor. If smoothing is enabled, the distribution is smoothed by
* exp(-difference^2/smoothing), where difference is the distance between the
* output value and the deterministic output value for the corresponding inputs.
*
* The variables are ordered as follows in the argument list:
*
* 1) Complex output (product of inputs)
* 2...) An arbitrary number of inputs (complex or real)
*
*/
public class ComplexProduct extends FactorFunction
{
protected double _beta = 0;
protected boolean _smoothingSpecified = false;
public ComplexProduct() {this(0);}
public ComplexProduct(double smoothing)
{
super();
if (smoothing > 0)
{
_beta = 1 / smoothing;
_smoothingSpecified = true;
}
}
@Override
public final double evalEnergy(Value[] arguments)
{
final int length = arguments.length;
final double[] out = arguments[0].getDoubleArray();
final double rOut = out[0];
final double iOut = out[1];
double rProduct = 1;
double iProduct = 0;
for (int i = 1; i < length; i++)
{
Value arg = arguments[i];
if (arg.getObject() instanceof double[]) // Complex input
{
final double[] in = arg.getDoubleArray();
final double rIn = in[0];
final double iIn = in[1];
final double rProductNext = rIn * rProduct - iIn * iProduct;
final double iProductNext = rIn * iProduct + iIn * rProduct;
rProduct = rProductNext;
iProduct = iProductNext;
}
else // Real input
{
final double in = arg.getDouble();
rProduct *= in;
iProduct *= in;
}
}
if (_smoothingSpecified)
{
final double rDiff = rProduct - rOut;
final double iDiff = iProduct - iOut;
final double potential = rDiff*rDiff + iDiff*iDiff;
return potential*_beta;
}
else
{
return (rProduct == rOut && iProduct == iOut) ? 0 : Double.POSITIVE_INFINITY;
}
}
@Override
public final boolean isDirected() {return true;}
@Override
public final int[] getDirectedToIndices() {return new int[]{0};}
@Override
public final boolean isDeterministicDirected() {return !_smoothingSpecified;}
@Override
public final void evalDeterministic(Value[] arguments)
{
final int length = arguments.length;
double rProduct = 1;
double iProduct = 0;
for (int i = 1; i < length; i++)
{
final Value arg = arguments[i];
if (arg.getObject() instanceof double[]) // Complex input
{
final double[] in = arg.getDoubleArray();
final double rIn = in[0];
final double iIn = in[1];
final double rProductNext = rIn * rProduct - iIn * iProduct;
final double iProductNext = rIn * iProduct + iIn * rProduct;
rProduct = rProductNext;
iProduct = iProductNext;
}
else // Real input
{
final Double in = arg.getDouble();
rProduct *= in;
iProduct *= in;
}
}
final double[] out = arguments[0].getDoubleArray();
out[0] = rProduct; // Replace the output value
out[1] = iProduct; // Replace the output value
}
}