Create a third m-file that implements the function mySumMat (mat) "that operates on a two-dimensional matrix. Use two while loops to sum up the arbitrary mumber of both rows and cohums in the matrix (This introduces the concept of nested loops. This function will also return a single scalar value representmg the sum of all elements in the matrix Test with matrices: [1,3,7,6;2,15,0,8] and [1,2,3; 4,5,6; 9,8,7] WAIT! YOU ARE NOT DONE - Whenever we build assumptions into our programs, we should test to ensure the assumptions are valid. In this case, we ASSUME the imput is a vector or matrix. The proper way to code this is to TEST to make sure they are vectors or matrices. If mySum ) ormyAve () are not passed a vector, return the error message ERROR: input must be one-dimensional vector. Consider all possibilities! If mySumMat () is not passed a 2-D array, return "ERROR: mput must be a two- dimensional matrix. These assumptions must ALSO be documented in the help