Need Help With Matlab Code

Now its your turn. Write a function (caesar.m) that takes as input two arguments: a string to encrypt and the key (shift value), and outputs a single argument which is a string containing the Caesar cipher encryption of the given string using the given key. The key may be positive (right shift) or negative (left shift). Your function should force the input to be uppercase and you should delete spaces and punctuation[1].

Example:

>> caesar('hello world',3)

ans =

KHOORZRUOG

[1] Equivalently, keep only letters.