@Test
public void testOnlyOneWayMatrixMultiplication() {
int[][] a = {{1, 2, 3, 4}, {5, 6, 7, 8}};
int[][] b = {{1}, {-1}, {1}, {-1}};
int[][] expected = {{-2}, {-2}};
try {
boolean equal = Arrays.deepEquals(expected, Matrix.multiply(a, b));
assertTrue(equal);
} catch (MatrixDimensionMismatchException e) {
fail("The matrix multiplication should work for mismatched (but tennable) matrices.");
}
boolean thrown = false;
try {
Matrix.multiply(b, a);
fail(
"The matrix multiplication was successful. It should have thrown a dimension mismatch exception");
;
} catch (MatrixDimensionMismatchException expectedException) {
thrown = true;
}
assertTrue(thrown);
}
@Test
public void testUnevenMatrixMultiplication() {
int[][] dataA = {{1, 2, 3}, {4, 5, 6}};
Matrix a = new Matrix(dataA);
int[][] dataB = {{1, 0}, {1, 1}, {0, 1}};
Matrix b = new Matrix(dataB);
int[][] expectedAB = {{3, 5}, {9, 11}};
int[][] expectedBA = {{1, 2, 3}, {5, 7, 9}, {4, 5, 6}};
try {
assertEquals(new Matrix(expectedBA), Matrix.multiply(b, a));
assertEquals(new Matrix(expectedAB), Matrix.multiply(a, b));
} catch (MatrixDimensionMismatchException e) {
fail("The matrix multiplicaiton should not have failed due to a size mismatch.");
}
}
@Test
public void testBasicSquareMatrixMultiplication() {
int[][] dataA = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
Matrix a = new Matrix(dataA);
int[][] dataB = {{0, 1, 0}, {1, 0, 1}, {1, 1, 0}};
Matrix b = new Matrix(dataB);
int[][] expectedAB = {{5, 4, 2}, {11, 10, 5}, {17, 16, 8}};
int[][] expectedBA = {{4, 5, 6}, {8, 10, 12}, {5, 7, 9}};
try {
assertEquals(new Matrix(expectedAB), Matrix.multiply(a, b));
assertEquals(new Matrix(expectedBA), Matrix.multiply(b, a));
} catch (MatrixDimensionMismatchException e) {
fail("The matrix multiplicaiton should not have failed due to a size mismatch.");
}
}
@Test
public void testUnevenIncorrectMatrixMultiplication() {
int[][] dataA = {{1, 2, 3}, {4, 5, 6}};
Matrix a = new Matrix(dataA);
boolean thrown = false;
try {
Matrix.multiply(a, a);
fail(
"The matrix multiplication was successful. It should have thrown a dimension mismatch exception");
;
} catch (MatrixDimensionMismatchException expectedException) {
thrown = true;
}
assertTrue(thrown);
}