cc.redberry.transformation.MinusRepresentationTo 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;

import cc.redberry.transformation.numbers.RemoveOneFromProduct;
import cc.redberry.core.tensor.Minus;
import cc.redberry.core.tensor.Product;
import cc.redberry.core.tensor.Tensor;
import cc.redberry.core.tensor.TensorNumber;

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

    @Override
    public Tensor transform(Tensor tensor) {
        if (tensor instanceof Product) {
            for (Tensor t : tensor)
                if (t instanceof TensorNumber && ((TensorNumber) t).factorOutSign())
                    return new Minus(RemoveOneFromProduct.INSTANCE.transform(tensor));
        }
        return tensor;
    }
}