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/*
* Copyright (C) 2017 The Android Open Source Project
*
* 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.
*/
package com.android.server.wifi.util;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotEquals;
import static org.junit.Assert.fail;
import androidx.test.filters.SmallTest;
import com.android.server.wifi.WifiBaseTest;
import org.junit.Test;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Random;
/**
* Unit tests for {@link com.android.server.wifi.util.Matrix}.
*/
@SmallTest
public class MatrixTest extends WifiBaseTest {
/**
* Test that both forms of constructor work
*/
@Test
public void testConstructors() throws Exception {
assertEquals(new Matrix(3, 2), new Matrix(2, new double[]{0, 0, 0, 0, 0, 0}));
}
/**
* Test some degenerate cases
*/
@Test
public void testDegenerate() throws Exception {
Matrix m1 = new Matrix(0, 20);
Matrix m2 = new Matrix(20, 0);
assertEquals(m1, m2.transpose());
}
/**
* Test addition
*/
@Test
public void testAddition() throws Exception {
Matrix m1 = new Matrix(2, new double[]{1, 2, 3, 4});
Matrix m2 = new Matrix(2, new double[]{10, 20, 30, 40});
Matrix m3 = new Matrix(2, new double[]{11, 22, 33, 44});
assertEquals(m3, m1.plus(m2));
}
/**
* Test subtraction.
*/
@Test
public void testSubtraction() throws Exception {
Matrix m1 = new Matrix(2, new double[]{1, 2, 3, 4});
Matrix m2 = new Matrix(2, new double[]{10, 20, 30, 40});
Matrix m3 = new Matrix(2, new double[]{11, 22, 33, 44});
assertEquals(m1, m3.minus(m2));
}
/**
* Test scalar multiplication.
*/
@Test
public void testScalarMultiplication() throws Exception {
Matrix m1 = new Matrix(2, new double[]{1, 2, 3, 4});
double x = 1001;
Matrix m2 = new Matrix(2, new double[]{x * 1, x * 2, x * 3, x * 4});
assertEquals(m2, m1.times(x));
}
/**
* Test matrix multiplication.
*/
@Test
public void testMultiplication() throws Exception {
Matrix m1 = new Matrix(2, new double[]{1, 2, 3, 4});
Matrix m2 = new Matrix(2, new double[]{-3, 3, 7, 1});
Matrix m3 = new Matrix(2, new double[]{11, 5, 19, 13});
assertEquals(m3, m1.dot(m2));
}
/**
* Test that matrix inverse works (non-singular case).
*/
@Test
public void testInverse() throws Exception {
Matrix i3 = new Matrix(3, new double[]{1, 0, 0, 0, 1, 0, 0, 0, 1});
Matrix f = new Matrix(3, new double[]{100, 100, 100, 100, 100, 100, 100, 100, 100});
Matrix m1 = new Matrix(3, new double[]{10, 1, -1, 2, 14, -1, 0, 2, 20});
Matrix m2 = m1.inverse();
Matrix m12 = m1.dot(m2);
Matrix m21 = m2.dot(m1);
// Add f here to wash out the roundoff errors
assertEquals(i3.plus(f), m12.plus(f));
assertEquals(i3.plus(f), m21.plus(f));
}
/**
* Generates a random permuation matrix
*/
public Matrix generatePermutationMatrix(int size, Random random) {
Matrix matrix = new Matrix(size, size);
ArrayList<Integer> j = new ArrayList(size);
for (int i = 0; i < size; i++) {
j.add(i);
}
Collections.shuffle(j, random);
for (int i = 0; i < size; i++) {
matrix.put(i, j.get(i), 1.0);
}
return matrix;
}
/**
* Test that inverting a random permutaion matrix works
*/
@Test
public void testInverseOfPermutation() throws Exception {
int size = 20;
Matrix m1 = generatePermutationMatrix(size, new Random(132));
Matrix m2 = m1.inverse();
Matrix m3 = m1.transpose();
assertEquals(m3, m2);
}
/**
* Test that attempting to invert a singular matrix throws an exception.
* @throws Exception
*/
@Test
public void testSingularity() throws Exception {
Matrix m1 = new Matrix(3, new double[]{10, 1, -1, 0, 0, 0, 0, 0, 0});
try {
m1.inverse();
fail("Expected ArithmeticException");
} catch (ArithmeticException e) {
return;
}
}
/**
* Test multiplication by a transpose
*/
@Test
public void testMultiplicationByTranspose() throws Exception {
Matrix m1 = new Matrix(2, new double[]{1, 2, 3, 4, 5, 6});
Matrix m2 = new Matrix(2, new double[]{1, 2, 3, 4, 5, 6, 7, 8});
assertEquals(m1.dot(m2.transpose()), m1.dotTranspose(m2));
}
/**
* Test that exception is thrown for non-conformable dotTranspose
*/
@Test
public void testMultiplicationByBadlyShapedTranspose() throws Exception {
Matrix m1 = new Matrix(2, new double[]{1, 2, 3, 4, 5, 6});
Matrix m2 = m1.transpose();
try {
m1.dotTranspose(m2);
fail("Expected IllegalArgumentException");
} catch (IllegalArgumentException e) {
}
}
/**
* Test that a copy is equal to the original, and that hash codes match,
* and that string versions match; exercise equals in various ways.
*/
@Test
public void testCopy() throws Exception {
Random random = new Random();
Matrix m1 = new Matrix(3, 4);
for (int i = 0; i < m1.mem.length; i++) {
m1.mem[i] = random.nextDouble();
}
assertEquals(m1, m1);
Matrix m2 = new Matrix(m1);
assertEquals(m1, m2);
assertEquals(m1.hashCode(), m2.hashCode());
assertEquals(m1.toString(), m2.toString());
m2.put(2, 2, 2.0); // guaranteed change, because nextDouble() is between 0 and 1.
assertNotEquals(m1, m2);
assertNotEquals(m1, m1.transpose());
assertNotEquals(m1.toString(), m2.toString());
assertNotEquals(m1, null);
assertNotEquals(m1, "a");
}
}
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