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

import org.apache.commons.math.MathException;
import org.apache.commons.math.linear.CholeskyDecompositionImpl;
import org.apache.commons.math.linear.DecompositionSolver;
import org.apache.commons.math.linear.MatrixUtils;
import org.apache.commons.math.linear.RealMatrix;
import org.apache.commons.math.linear.ArrayRealVector;

public class CholeskySolverTest extends TestCase {

	private double[][] testData = new double[][] { { 1, 2, 4, 7, 11 }, { 2, 13, 23, 38, 58 }, { 4, 23, 77, 122, 182 },
			{ 7, 38, 122, 294, 430 }, { 11, 58, 182, 430, 855 } };

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

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

	/** test solve dimension errors */
	public void testSolveDimensionErrors() throws MathException {
		DecompositionSolver solver = new CholeskyDecompositionImpl(MatrixUtils.createRealMatrix(testData)).getSolver();
		RealMatrix b = MatrixUtils.createRealMatrix(new double[2][2]);
		try {
			solver.solve(b);
			fail("an exception should have been thrown");
		} catch (IllegalArgumentException iae) {
			// expected behavior
		} catch (Exception e) {
			fail("wrong exception caught");
		}
		try {
			solver.solve(b.getColumn(0));
			fail("an exception should have been thrown");
		} catch (IllegalArgumentException iae) {
			// expected behavior
		} catch (Exception e) {
			fail("wrong exception caught");
		}
		try {
			solver.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() throws MathException {
		DecompositionSolver solver = new CholeskyDecompositionImpl(MatrixUtils.createRealMatrix(testData)).getSolver();
		RealMatrix b = MatrixUtils.createRealMatrix(new double[][] { { 78, -13, 1 }, { 414, -62, -1 },
				{ 1312, -202, -37 }, { 2989, -542, 145 }, { 5510, -1465, 201 } });
		RealMatrix xRef = MatrixUtils
				.createRealMatrix(new double[][] { { 1, 0, 1 }, { 0, 1, 1 }, { 2, 1, -4 }, { 2, 2, 2 }, { 5, -3, 0 } });

		// using RealMatrix
		assertEquals(0, solver.solve(b).subtract(xRef).getNorm(), 1.0e-13);

		// using double[]
		for (int i = 0; i < b.getColumnDimension(); ++i) {
			assertEquals(0,
					new ArrayRealVector(solver.solve(b.getColumn(i))).subtract(xRef.getColumnVector(i)).getNorm(),
					1.0e-13);
		}

		// using ArrayRealVector
		for (int i = 0; i < b.getColumnDimension(); ++i) {
			assertEquals(0, solver.solve(b.getColumnVector(i)).subtract(xRef.getColumnVector(i)).getNorm(), 1.0e-13);
		}

		// using RealVector with an alternate implementation
		for (int i = 0; i < b.getColumnDimension(); ++i) {
			ArrayRealVectorTest.RealVectorTestImpl v = new ArrayRealVectorTest.RealVectorTestImpl(b.getColumn(i));
			assertEquals(0, solver.solve(v).subtract(xRef.getColumnVector(i)).getNorm(), 1.0e-13);
		}

	}

	/** test determinant */
	public void testDeterminant() throws MathException {
		assertEquals(7290000.0, getDeterminant(MatrixUtils.createRealMatrix(testData)), 1.0e-15);
	}

	private double getDeterminant(RealMatrix m) throws MathException {
		return new CholeskyDecompositionImpl(m).getDeterminant();
	}

}
