/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.math.linear;

import java.util.Random;

import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;

import org.apache.commons.math.linear.DecompositionSolver;
import org.apache.commons.math.linear.EigenDecompositionImpl;
import org.apache.commons.math.linear.InvalidMatrixException;
import org.apache.commons.math.linear.MatrixUtils;
import org.apache.commons.math.linear.RealMatrix;
import org.apache.commons.math.linear.ArrayRealVector;
import org.apache.commons.math.util.MathUtils;

public class EigenSolverTest extends TestCase {

	private double[] refValues;
	private RealMatrix matrix;

	public EigenSolverTest(String name) {
		super(name);
	}

	public static Test suite() {
		TestSuite suite = new TestSuite(EigenSolverTest.class);
		suite.setName("EigenSolver Tests");
		return suite;
	}

	/** test non invertible matrix */
	public void testNonInvertible() {
		Random r = new Random(9994100315209l);
		RealMatrix m = EigenDecompositionImplTest.createTestMatrix(r, new double[] { 1.0, 0.0, -1.0, -2.0, -3.0 });
		DecompositionSolver es = new EigenDecompositionImpl(m, MathUtils.SAFE_MIN).getSolver();
		assertFalse(es.isNonSingular());
		try {
			es.getInverse();
			fail("an exception should have been thrown");
		} catch (InvalidMatrixException ime) {
			// expected behavior
		} catch (Exception e) {
			fail("wrong exception caught");
		}
	}

	/** test invertible matrix */
	public void testInvertible() {
		Random r = new Random(9994100315209l);
		RealMatrix m = EigenDecompositionImplTest.createTestMatrix(r, new double[] { 1.0, 0.5, -1.0, -2.0, -3.0 });
		DecompositionSolver es = new EigenDecompositionImpl(m, MathUtils.SAFE_MIN).getSolver();
		assertTrue(es.isNonSingular());
		RealMatrix inverse = es.getInverse();
		RealMatrix error = m.multiply(inverse).subtract(MatrixUtils.createRealIdentityMatrix(m.getRowDimension()));
		assertEquals(0, error.getNorm(), 4.0e-15);
	}

	/** test solve dimension errors */
	public void testSolveDimensionErrors() {
		DecompositionSolver es = new EigenDecompositionImpl(matrix, MathUtils.SAFE_MIN).getSolver();
		RealMatrix b = MatrixUtils.createRealMatrix(new double[2][2]);
		try {
			es.solve(b);
			fail("an exception should have been thrown");
		} catch (IllegalArgumentException iae) {
			// expected behavior
		} catch (Exception e) {
			fail("wrong exception caught");
		}
		try {
			es.solve(b.getColumn(0));
			fail("an exception should have been thrown");
		} catch (IllegalArgumentException iae) {
			// expected behavior
		} catch (Exception e) {
			fail("wrong exception caught");
		}
		try {
			es.solve(new ArrayRealVectorTest.RealVectorTestImpl(b.getColumn(0)));
			fail("an exception should have been thrown");
		} catch (IllegalArgumentException iae) {
			// expected behavior
		} catch (Exception e) {
			fail("wrong exception caught");
		}
	}

	/** test solve */
	public void testSolve() {
		RealMatrix m = MatrixUtils.createRealMatrix(new double[][] { { 91, 5, 29, 32, 40, 14 }, { 5, 34, -1, 0, 2, -1 },
				{ 29, -1, 12, 9, 21, 8 }, { 32, 0, 9, 14, 9, 0 }, { 40, 2, 21, 9, 51, 19 }, { 14, -1, 8, 0, 19, 14 } });
		DecompositionSolver es = new EigenDecompositionImpl(m, MathUtils.SAFE_MIN).getSolver();
		RealMatrix b = MatrixUtils.createRealMatrix(new double[][] { { 1561, 269, 188 }, { 69, -21, 70 },
				{ 739, 108, 63 }, { 324, 86, 59 }, { 1624, 194, 107 }, { 796, 69, 36 } });
		RealMatrix xRef = MatrixUtils.createRealMatrix(
				new double[][] { { 1, 2, 1 }, { 2, -1, 2 }, { 4, 2, 3 }, { 8, -1, 0 }, { 16, 2, 0 }, { 32, -1, 0 } });

		// using RealMatrix
		assertEquals(0, es.solve(b).subtract(xRef).getNorm(), 2.0e-12);

		// using double[]
		for (int i = 0; i < b.getColumnDimension(); ++i) {
			assertEquals(0, new ArrayRealVector(es.solve(b.getColumn(i))).subtract(xRef.getColumnVector(i)).getNorm(),
					2.0e-11);
		}

		// using Array2DRowRealMatrix
		for (int i = 0; i < b.getColumnDimension(); ++i) {
			assertEquals(0, es.solve(b.getColumnVector(i)).subtract(xRef.getColumnVector(i)).getNorm(), 2.0e-11);
		}

		// using RealMatrix with an alternate implementation
		for (int i = 0; i < b.getColumnDimension(); ++i) {
			ArrayRealVectorTest.RealVectorTestImpl v = new ArrayRealVectorTest.RealVectorTestImpl(b.getColumn(i));
			assertEquals(0, es.solve(v).subtract(xRef.getColumnVector(i)).getNorm(), 2.0e-11);
		}

	}

	@Override
	public void setUp() {
		refValues = new double[] { 2.003, 2.002, 2.001, 1.001, 1.000, 0.001 };
		matrix = EigenDecompositionImplTest.createTestMatrix(new Random(35992629946426l), refValues);
	}

	@Override
	public void tearDown() {
		refValues = null;
		matrix = null;
	}

}
