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A 100% Java sparse and dense matrix library.

There is a newer version: 0.6.0

/*
 * Copyright 2011-2013, by Vladimir Kostyukov and Contributors.
 * 
 * This file is part of la4j project (http://la4j.org)
 * 
 * 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.
 * 
 * Contributor(s): -
 * 
 */

package org.la4j.inversion;

import org.la4j.factory.Factory;
import org.la4j.linear.LinearSystem;
import org.la4j.matrix.Matrices;
import org.la4j.matrix.Matrix;
import org.la4j.vector.Vector;

public class GaussianInvertor implements MatrixInvertor {

    @Override
    public Matrix inverse(Matrix matrix, Factory factory) {

        if (matrix.rows() != matrix.columns()) {
            throw new IllegalArgumentException("Wrong matrix size: " 
                    + "rows != columns");
        }

        Matrix result = factory.createMatrix(matrix.rows(), matrix.columns());

        for (int i = 0; i < matrix.rows(); i++) {

            Vector b = factory.createVector(matrix.rows());
            b.set(i, 1.0);

            LinearSystem system = factory.createLinearSystem(matrix, b);
            Vector x = system.solve(Matrices.GAUSSIAN_SOLVER);

            result.setColumn(i, x);
        }

        return result;
    }
}