Add exercise subject for matrix_transposition_4by3

subjects/matrix_transposition/README.md

@@ -13,7 +13,7 @@
 Example:
 
 ```
-( a b )     __ transposition __> ( a d )
+( a b )   __ transposition __>   ( a d )
 ( c d )                          ( b d )
 ```
 

subjects/matrix_transposition_4by3/README.md

@@ -0,0 +1,67 @@
+## matrix_transposition
+
+### Instructions
+
+- Define the structure matrix as a tuple of tuples of `i32`'s
+
+- Define a function that calculate the transpose matrix of a 4x3 matrix (4 rows by 3 columns) which is a 3x4 matrix (3 rows by 4 columns).
+
+- Note:
+
+	- The transpose of a matrix `A` is the matrix `A'` where `A'`'s columns are `A`'s row and the rows are the columns:
+
+Example:
+
+```
+( a b )   __ transposition __>   ( a d )
+( c d )                          ( b d )
+```
+
+- Matrix must implement Debug, PartialEq and Eq. You can use derive
+
+- Remember that you're defining a library so you have to make public the elements that are going to be called from an external crate.
+
+### Notions
+
+[Chapter 7]( https://doc.rust-lang.org/stable/book/ch07-03-paths-for-referring-to-an-item-in-the-module-tree.html )
+
+### Expected Function
+
+```rust
+pub struct Matrix4by3(
+	pub (i32, i32, i32),
+	pub (i32, i32, i32),
+	pub (i32, i32, i32),
+	pub (i32, i32, i32),
+);
+
+pub struct Matrix3by4(
+	pub (i32, i32, i32, i32),
+	pub (i32, i32, i32, i32),
+	pub (i32, i32, i32, i32),
+);
+
+pub fn transpose(m: Matrix4by3) -> Matrix3by4 {
+}
+```
+
+### Usage
+
+Here is a posible program to test your function
+
+```rust
+fn main() {
+	let matrix = Matrix4by3((1, 2, 3), (4, 5, 6), (7, 8, 9), (10, 11, 12));
+    println!("Original matrix {:?}", matrix);
+    println!("Transpose matrix {:?}", transpose(matrix));
+}
+```
+
+And it's output:
+
+```console
+student@ubuntu:~/[[ROOT]]/test$ cargo run
+Original matrix Matrix4by3((1, 2, 3), (4, 5, 6), (7, 8, 9), (10, 11, 12))
+Transpose matrix Matrix3by4((1, 4, 7, 10), (2, 5, 8, 11), (3, 6, 9, 12))
+student@ubuntu:~/[[ROOT]]/test$
+```