/*******************************************************************************
* Copyright 2014 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 conversion of a vector of two real variables to a complex variable.
* 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) Output (Complex vector)
* 2) Input real-part (Real)
* 3) Input imaginary-part (Real)
*
* @since 0.07
*/
public class RealAndImaginaryToComplex extends FactorFunction
{
private double _beta = 0;
private boolean _smoothingSpecified = false;
public RealAndImaginaryToComplex() {this(0);}
public RealAndImaginaryToComplex(double smoothing)
{
super();
if (smoothing > 0)
{
_beta = 1 / smoothing;
_smoothingSpecified = true;
}
}
@Override
public final double evalEnergy(Value[] arguments)
{
// Output Complex
final double[] complex = arguments[0].getDoubleArray();
if (_smoothingSpecified)
{
final double diffR = arguments[1].getDouble() - complex[0];
final double diffI = arguments[2].getDouble() - complex[1];
return _beta * ((diffR*diffR) + (diffI*diffI));
}
else
{
if (arguments[1].getDouble() != complex[0])
return Double.POSITIVE_INFINITY;
else if (arguments[2].getDouble() != complex[1])
return Double.POSITIVE_INFINITY;
else
return 0;
}
}
@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)
{
// Output Complex
final double[] complex = arguments[0].getDoubleArray();
complex[0] = arguments[1].getDouble();
complex[1] = arguments[2].getDouble();
}
}