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Nishitha0730Nishitha0730
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Updated files with google-java-format
1 parent d150bb2 commit 1858c69

2 files changed

Lines changed: 109 additions & 113 deletions

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‎src/main/java/com/thealgorithms/matrix/MatrixMultiplication.java‎

Lines changed: 38 additions & 39 deletions
Original file line numberDiff line numberDiff line change
@@ -1,51 +1,50 @@
11
package com.thealgorithms.matrix;
22

33
public final class MatrixMultiplication {
4-
private MatrixMultiplication() {
5-
}
4+
private MatrixMultiplication() {}
65

7-
/**
8-
* Multiplies two matrices.
9-
*
10-
* @param matrixA the first matrix rowsA x colsA
11-
* @param matrixB the second matrix rowsB x colsB
12-
* @return the product of the two matrices rowsA x colsB
13-
* @throws IllegalArgumentException if the matrices cannot be multiplied
14-
*/
15-
public static double[][] multiply(double[][] matrixA, double[][] matrixB) {
16-
// Check the input matrices are not null
17-
if (matrixA == null || matrixB == null) {
18-
throw new IllegalArgumentException("Input matrices cannot be null");
19-
}
6+
/**
7+
* Multiplies two matrices.
8+
*
9+
* @param matrixA the first matrix rowsA x colsA
10+
* @param matrixB the second matrix rowsB x colsB
11+
* @return the product of the two matrices rowsA x colsB
12+
* @throws IllegalArgumentException if the matrices cannot be multiplied
13+
*/
14+
public static double[][] multiply(double[][] matrixA, double[][] matrixB) {
15+
// Check the input matrices are not null
16+
if (matrixA == null || matrixB == null) {
17+
throw new IllegalArgumentException("Input matrices cannot be null");
18+
}
2019

21-
// Check for empty matrices
22-
if (matrixA.length == 0
23-
|| matrixB.length == 0
24-
|| matrixA[0].length == 0
25-
|| matrixB[0].length == 0) {
26-
throw new IllegalArgumentException("Input matrices must not be empty");
27-
}
20+
// Check for empty matrices
21+
if (matrixA.length == 0
22+
|| matrixB.length == 0
23+
|| matrixA[0].length == 0
24+
|| matrixB[0].length == 0) {
25+
throw new IllegalArgumentException("Input matrices must not be empty");
26+
}
2827

29-
// Validate the matrix dimensions
30-
if (matrixA[0].length != matrixB.length) {
31-
throw new IllegalArgumentException("Matrices cannot be multiplied: incompatible dimensions.");
32-
}
28+
// Validate the matrix dimensions
29+
if (matrixA[0].length != matrixB.length) {
30+
throw new IllegalArgumentException("Matrices cannot be multiplied: incompatible dimensions.");
31+
}
3332

34-
int rowsA = matrixA.length;
35-
int colsA = matrixA[0].length;
36-
int colsB = matrixB[0].length;
33+
int rowsA = matrixA.length;
34+
int colsA = matrixA[0].length;
35+
int colsB = matrixB[0].length;
3736

38-
// Initialize the result matrix with zeros
39-
double[][] result = new double[rowsA][colsB];
37+
// Initialize the result matrix with zeros
38+
double[][] result = new double[rowsA][colsB];
4039

41-
// Perform matrix multiplication
42-
for (int i = 0; i < rowsA; i++) {
43-
for (int j = 0; j < colsB; j++) {
44-
for (int k = 0; k < colsA; k++) {
45-
result[i][j] += matrixA[i][k] * matrixB[k][j];
46-
}
47-
}
40+
// Perform matrix multiplication
41+
for (int i = 0; i < rowsA; i++) {
42+
for (int j = 0; j < colsB; j++) {
43+
for (int k = 0; k < colsA; k++) {
44+
result[i][j] += matrixA[i][k] * matrixB[k][j];
4845
}
49-
return result;
46+
}
5047
}
48+
return result;
49+
}
5150
}

‎src/test/java/com/thealgorithms/matrix/MatrixMultiplicationTest.java‎

Lines changed: 71 additions & 74 deletions
Original file line numberDiff line numberDiff line change
@@ -7,79 +7,76 @@
77

88
public class MatrixMultiplicationTest {
99

10-
private static final double EPSILON = 1e-9; // for floating point comparison
11-
12-
@Test
13-
void testMultiply2by2() {
14-
double[][] matrixA = {{1.0, 2.0}, {3.0, 4.0}};
15-
double[][] matrixB = {{5.0, 6.0}, {7.0, 8.0}};
16-
double[][] expected = {{19.0, 22.0}, {43.0, 50.0}};
17-
18-
double[][] result = MatrixMultiplication.multiply(matrixA, matrixB);
19-
assertMatrixEquals(expected, result); // Use custom method due to floating point issues
20-
}
21-
22-
@Test
23-
void testMultiply3by2and2by1() {
24-
double[][] matrixA = {{1.0, 2.0}, {3.0, 4.0}, {5.0, 6.0}};
25-
double[][] matrixB = {{7.0}, {8.0}};
26-
double[][] expected = {{23.0}, {53.0}, {83.0}};
27-
28-
double[][] result = MatrixMultiplication.multiply(matrixA, matrixB);
29-
assertMatrixEquals(expected, result);
30-
}
31-
32-
@Test
33-
void testNullMatrixA() {
34-
double[][] b = {{1, 2}, {3, 4}};
35-
assertThrows(IllegalArgumentException.class,
36-
() -> MatrixMultiplication.multiply(null, b));
37-
}
38-
39-
@Test
40-
void testNullMatrixB() {
41-
double[][] a = {{1, 2}, {3, 4}};
42-
assertThrows(IllegalArgumentException.class,
43-
() -> MatrixMultiplication.multiply(a, null));
44-
}
45-
46-
@Test
47-
void testMultiplyNull() {
48-
double[][] matrixA = {{1.0, 2.0}, {3.0, 4.0}};
49-
double[][] matrixB = null;
50-
51-
Exception exception = assertThrows(IllegalArgumentException.class,
52-
() -> MatrixMultiplication.multiply(matrixA, matrixB));
53-
54-
String expectedMessage = "Input matrices cannot be null";
55-
String actualMessage = exception.getMessage();
56-
57-
assertTrue(actualMessage.contains(expectedMessage));
58-
}
59-
60-
@Test
61-
void testIncompatibleDimensions() {
62-
double[][] a = {{1.0, 2.0}};
63-
double[][] b = {{1.0, 2.0}};
64-
assertThrows(IllegalArgumentException.class,
65-
() -> MatrixMultiplication.multiply(a, b));
66-
}
67-
68-
@Test
69-
void testEmptyMatrices() {
70-
double[][] a = new double[0][0];
71-
double[][] b = new double[0][0];
72-
assertThrows(IllegalArgumentException.class,
73-
() -> MatrixMultiplication.multiply(a, b));
74-
}
75-
76-
private void assertMatrixEquals(double[][] expected, double[][] actual) {
77-
assertEquals(expected.length, actual.length, "Row count mismatch");
78-
for (int i = 0; i < expected.length; i++) {
79-
assertEquals(expected[i].length, actual[i].length, "Column count mismatch at row " + i);
80-
for (int j = 0; j < expected[i].length; j++) {
81-
assertEquals(expected[i][j], actual[i][j], EPSILON, "Mismatch at (" + i + "," + j + ")");
82-
}
83-
}
10+
private static final double EPSILON = 1e-9; // for floating point comparison
11+
12+
@Test
13+
void testMultiply2by2() {
14+
double[][] matrixA = {{1.0, 2.0}, {3.0, 4.0}};
15+
double[][] matrixB = {{5.0, 6.0}, {7.0, 8.0}};
16+
double[][] expected = {{19.0, 22.0}, {43.0, 50.0}};
17+
18+
double[][] result = MatrixMultiplication.multiply(matrixA, matrixB);
19+
assertMatrixEquals(expected, result); // Use custom method due to floating point issues
20+
}
21+
22+
@Test
23+
void testMultiply3by2and2by1() {
24+
double[][] matrixA = {{1.0, 2.0}, {3.0, 4.0}, {5.0, 6.0}};
25+
double[][] matrixB = {{7.0}, {8.0}};
26+
double[][] expected = {{23.0}, {53.0}, {83.0}};
27+
28+
double[][] result = MatrixMultiplication.multiply(matrixA, matrixB);
29+
assertMatrixEquals(expected, result);
30+
}
31+
32+
@Test
33+
void testNullMatrixA() {
34+
double[][] b = {{1, 2}, {3, 4}};
35+
assertThrows(IllegalArgumentException.class, () -> MatrixMultiplication.multiply(null, b));
36+
}
37+
38+
@Test
39+
void testNullMatrixB() {
40+
double[][] a = {{1, 2}, {3, 4}};
41+
assertThrows(IllegalArgumentException.class, () -> MatrixMultiplication.multiply(a, null));
42+
}
43+
44+
@Test
45+
void testMultiplyNull() {
46+
double[][] matrixA = {{1.0, 2.0}, {3.0, 4.0}};
47+
double[][] matrixB = null;
48+
49+
Exception exception =
50+
assertThrows(
51+
IllegalArgumentException.class, () -> MatrixMultiplication.multiply(matrixA, matrixB));
52+
53+
String expectedMessage = "Input matrices cannot be null";
54+
String actualMessage = exception.getMessage();
55+
56+
assertTrue(actualMessage.contains(expectedMessage));
57+
}
58+
59+
@Test
60+
void testIncompatibleDimensions() {
61+
double[][] a = {{1.0, 2.0}};
62+
double[][] b = {{1.0, 2.0}};
63+
assertThrows(IllegalArgumentException.class, () -> MatrixMultiplication.multiply(a, b));
64+
}
65+
66+
@Test
67+
void testEmptyMatrices() {
68+
double[][] a = new double[0][0];
69+
double[][] b = new double[0][0];
70+
assertThrows(IllegalArgumentException.class, () -> MatrixMultiplication.multiply(a, b));
71+
}
72+
73+
private void assertMatrixEquals(double[][] expected, double[][] actual) {
74+
assertEquals(expected.length, actual.length, "Row count mismatch");
75+
for (int i = 0; i < expected.length; i++) {
76+
assertEquals(expected[i].length, actual[i].length, "Column count mismatch at row " + i);
77+
for (int j = 0; j < expected[i].length; j++) {
78+
assertEquals(expected[i][j], actual[i][j], EPSILON, "Mismatch at (" + i + "," + j + ")");
79+
}
8480
}
81+
}
8582
}

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