cc.redberry.transformation.integral.ExpandIntegral Maven / Gradle / Ivy

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/*
 * Redberry: symbolic tensor computations.
 *
 * Copyright (c) 2010-2012:
 *   Stanislav Poslavsky   
 *   Bolotin Dmitriy       
 *
 * This file is part of Redberry.
 *
 * Redberry is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Redberry is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Redberry. If not, see .
 */
package cc.redberry.transformation.integral;

import cc.redberry.core.tensor.Integral;
import cc.redberry.core.tensor.SimpleTensor;
import cc.redberry.core.tensor.Sum;
import cc.redberry.core.tensor.Tensor;
import cc.redberry.transformation.Transformation;

/**
 *
 * @author Stanislav Poslavsky
 */
public class ExpandIntegral implements Transformation {
    public static final ExpandIntegral INSTANCE = new ExpandIntegral();

    private ExpandIntegral() {
    }

    @Override
    public Tensor transform(final Tensor tensor) {
        if (!(tensor instanceof Integral))
            return tensor;
        final Integral integral = (Integral) tensor;
        final Tensor target = integral.target();
        final SimpleTensor[] vars = integral.vars();
        if (!(target instanceof Sum))
            return tensor;
        Sum result = new Sum();
        for (Tensor summand : target)
            result.add(new Integral(summand.clone(), clone(vars)));
        return result;
    }

    private static SimpleTensor[] clone(final SimpleTensor[] a) {
        final SimpleTensor[] r = new SimpleTensor[a.length];
        for (int i = 0; i < a.length; ++i)
            r[i] = a[i].clone();
        return r;
    }
}