$3\mathrm{.}8$ Develop an M$-$file function that is passed a numeric grade from $0$ to $100$ and

returns a letter grade according to the scheme:

The first line of the function should be

FIGURE P$3\mathrm{.}10$

Design the function so that it displays an error message and terminates in the event

that the user enters a value of score that is less than zero or greater than $100.$ Test

your function with $89\mathrm{.}9999,90,45,$ and $120.$