how can i do not traverse through unnecessary rows and columns that are filled with zeros in part 3?

Part 1: You will define the banded matrix A. Each of the entries inside the band (i.e. non-zero elements) will be some random number i.e., A(i, j random) Outside of the band, A(I, j)0 This matrix will be user-defined which means that the band size (m) and overall size of the matrix (N are inputs to the function. We will assume that m