Function for matrix in R : <p>I'm new (very new) in R. I'm struggling with making a function that's supposed to take a matrix (old_matrix) and return a new matrix (new_matrix), but in new_matrix all values in old_matrix that is a prime should be multiplied by 2 when it appears in new_matrix. So the new matrix should look the same as the old matrix, but where a prime occurs in old, this element should be multiplied by 2. </p>

<p>I'm thinking that I should start out with a for loop, but I'm already struggling with how to make the loop go through all elements of the matrix. I appreciate all the help I can get to get closer to making this function!</p>
