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Tensorics is a java framework which uses a tensor as a central object. A tensor represents a set of values placed in an N-dimensional space. Wherever you are tempted to use maps of maps, a tensor might be a good choice ;-) Tensorics provides methods to create, transform and performing calculations with those tensors.

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// @formatter:off
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 *
 * This file is part of tensorics.
 * 
 * Copyright (c) 2008-2011, CERN. All rights reserved.
 *
 * 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.
 * 
 ******************************************************************************/
// @formatter:on

package org.tensorics.core.tensor.lang;

import org.tensorics.core.commons.lang.OngoingOperation;
import org.tensorics.core.commons.options.Environment;
import org.tensorics.core.iterable.operations.IterableSum;
import org.tensorics.core.lang.Tensorics;
import org.tensorics.core.math.operations.BinaryOperation;
import org.tensorics.core.tensor.Tensor;
import org.tensorics.core.tensor.operations.ElementBinaryOperation;
import org.tensorics.core.tensor.operations.InnerTensorOperation;

/**
 * Part of the fluent API for operations on tensors.
 * 
 * @author agorzaws, kfuchbe
 * @param 
 * @param 
 */
public class OngoingTensorOperation implements OngoingOperation, V> {

    private final Environment environment;
    private final Tensor left;

    /**
     * @param environment the environment to use
     * @param left first tensoric to use
     */
    public OngoingTensorOperation(Environment environment, Tensor left) {
        this.environment = environment;
        this.left = left;
    }

    /**
     * Returns the sum of the left tensor with the given right tensor.
     * 
     * @param right as tensor to add
     * @return result of summing two tensors
     */
    @Override
    public Tensor plus(Tensor right) {
        return evaluate(right, environment.field().addition());
    }

    @Override
    public Tensor minus(Tensor right) {
        return evaluate(right, environment.field().subtraction());
    }

    /**
     * Calls multiplication operation on the elements of the two input tensors
     * 
     * @param right second tensoric to use
     * @return A tensor, containing elements that are the product of the respecive elemtents of the two input tensors
     */
    @Override
    public Tensor elementTimes(Tensor right) {
        return evaluate(right, environment.field().multiplication());
    }

    @Override
    public Tensor elementDividedByV(V value) {
        return elementDividedBy(Tensorics.zeroDimensionalOf(value));
    }

    private Tensor evaluate(Tensor right, BinaryOperation operation) {
        return new ElementBinaryOperation(operation, environment.options()).perform(left, right);
    }

    @Override
    public Tensor elementTimesV(V right) {
        return elementTimes(Tensorics.zeroDimensionalOf(right));
    }

    @Override
    public Tensor elementDividedBy(Tensor right) {
        return evaluate(right, environment.field().division());
    }

    /**
     * Performs the inner tensor product of the left tensor with the right tensor by taking care about co-and
     * contravariant coordinates and following the tensoric-equivalen of Einsteins sum convention.
     * 
     * @param right the right tensor to multiply onto the left
     * @return a tensor resulting from the multiplication
     * @see InnerTensorOperation
     */
    public Tensor times(Tensor right) {
        return new InnerTensorOperation(environment.field().multiplication(),
                new IterableSum<>(environment.field()), environment.options()).perform(left, right);
    }

}