Add test and subject of exercise `matrix_mult`

rust/tests/matrix_mult_test/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "lalgebra_scalar"
+version = "0.1.0"
+
+[[package]]
+name = "matrix"
+version = "0.1.0"
+dependencies = [
+ "lalgebra_scalar",
+]
+
+[[package]]
+name = "matrix_test"
+version = "0.1.0"
+dependencies = [
+ "matrix",
+]

rust/tests/matrix_mult_test/Cargo.toml

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+[package]
+name = "matrix_test"
+version = "0.1.0"
+authors = ["Augusto <aug.ornelas@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+matrix = { path = "../../../../rust-piscine-solutions/matrix"}

rust/tests/matrix_mult_test/src/main.rs

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+// Now define the matrix multiplication by implementing the
+// std::ops::Mul for the type matrix
+
+use matrix::Matrix;
+
+fn main() {
+	let matrix: Matrix<u32> = Matrix(vec![vec![3, 6], vec![8, 0]]);
+	println!("{:?}", matrix.col(0));
+	println!("{:?}", matrix.row(1));
+
+	let matrix_1: Matrix<u32> = Matrix(vec![vec![0, 1], vec![0, 0]]);
+	let matrix_2: Matrix<u32> = Matrix(vec![vec![0, 0], vec![1, 0]]);
+	let mult = matrix_1.clone() * matrix_2.clone();
+	println!("{:?}", mult);
+	println!("{:?}", matrix_1.number_of_cols());
+	println!("{:?}", matrix_2.number_of_rows());
+}
+
+#[test]
+fn get_row() {
+	let matrix: Matrix<u32> = Matrix(vec![vec![3, 6], vec![8, 0]]);
+	assert_eq!(vec![3u32, 6], matrix.row(0));
+	assert_eq!(vec![8u32, 0], matrix.row(1));
+}
+
+#[test]
+fn get_col() {
+	let matrix: Matrix<u32> = Matrix(vec![vec![3, 6], vec![8, 0]]);
+	assert_eq!(matrix.col(0), vec![3u32, 8]);
+	assert_eq!(vec![6u32, 0], matrix.col(1));
+}
+
+#[test]
+fn matrix_multiplication() {
+	let matrix_1: Matrix<u32> = Matrix(vec![vec![0, 1], vec![0, 0]]);
+	let matrix_2: Matrix<u32> = Matrix(vec![vec![0, 0], vec![1, 0]]);
+	let expected: Matrix<u32> = Matrix(vec![vec![1, 0], vec![0, 0]]);
+	assert_eq!(matrix_1 * matrix_2, Some(expected));
+
+	let matrix_1: Matrix<u32> = Matrix(vec![vec![0, 1], vec![0, 0]]);
+	let matrix_2: Matrix<u32> = Matrix(vec![vec![0, 0, 0], vec![1, 0, 0], vec![1, 1, 1]]);
+	assert_eq!(matrix_1 * matrix_2, None);
+}

subjects/matrix_mult/README.md

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+## matrix_mult
+
+### Instructions
+
+Implement the methods:
+
+- `number_of_cols` which returns the number of columns of the matrix.
+
+- `number_of_rows` which returns the number of rows of the matrix.
+
+- `row(n)` which returns the `n`th row in the matrix.
+
+- `col(n)` which returns the `n`th
+
+Define the matrix multiplication by implementing the std::ops::Mul for the type matrix
+
+### Expected Functions
+
+```rust
+impl Matrix<T> {
+	pub fn number_of_cols(&self) -> usize {
+	}
+
+	pub fn rows(&self) -> usize {
+	}
+
+	pub fn number_of_row(&self, n: usize) -> Vec<T> {
+	}
+
+	pub fn col(&self, n: usize) -> Vec<T> {
+	}
+}
+
+impl Mul for Matrix<T> {
+}
+```
+
+### Usage
+
+Here is a program to test your function.
+
+```rust
+fn main() {
+	let matrix: Matrix<u32> = Matrix(vec![vec![3, 6], vec![8, 0]]);
+	println!("{:?}", matrix.col(0));
+	println!("{:?}", matrix.row(1));
+
+	let matrix_1: Matrix<u32> = Matrix(vec![vec![0, 1], vec![0, 0]]);
+	let matrix_2: Matrix<u32> = Matrix(vec![vec![0, 0], vec![1, 0]]);
+	let mult = matrix_1.clone() * matrix_2.clone();
+	println!("{:?}", mult);
+	println!("{:?}", matrix_1.number_of_cols());
+	println!("{:?}", matrix_2.number_of_rows());
+}
+```
+
+And its output
+
+```console
+student@ubuntu:~/[[ROOT]]/test$ cargo run
+[3, 8]
+[8, 0]
+Some(Matrix([[1, 0], [0, 0]]))
+2
+2
+student@ubuntu:~/[[ROOT]]/test$
+```