3. Write an anonymous matlab function that takes as its input argument a one-dimensional array of numbers (a vector) and returns the average of the elements in the array, WITHOUT using the built-in mean function (Hint: use the sum and length functions instead.) Use your function to calculate the average of any numerical vector. 4. Write a custom matlab function m-file that takes as its input arguments a vector of any length. The function should return two vectors, with the first vector consisting of the 1sthalf of the input vector and the second vector consisting of the 2ndhalf. This must work whether your vector has an even or odd length. Use the length and fix functions to help with this. (Hint: Try to do it with a vector of even length first. 5. Determine (and demonstrate) the matlab code for accessing the submatrix from row m-2 to m-1 and column n-2 to n-1 of any mxn matrix (that is at least 3x3)