(20 points) Write a Matlab script that request the user to provide rmax, a number larger than zero. Then, the code will plot the next function on the interval [0,rmax]: M(r)=[ebrcos(ara)+r3ecrsin(ak(ra))] with k=4,a=2,b=3,c=1. The plot should include axis labels and title. If the given number is not positive, then the code should display an error message, otherwise the plot should be displayed. Add comments to your script to describe what is being done at every part of the code