Produce R code that takes an integer n and an integer matrix mat of size n × n and computes and displays the sum of each column in the matrix using mclapply. Modify your code from problem 4 to...

Produce R code that takes an integer n and an integer matrix mat of size n × n and computes and displays the sum of each column in the matrix using mclapply.

Modify your code from problem 4 to calculate the sum of every other number in each column, starting with the first (i.e., if n equals six, add the first, third, and fifth numbers in each column together).