Normal Stress of a Bar with Graph

Normal Stress of a Bar with Graph, use of clearvars, use of graph parameters.

Template to serve as example of a 1D graph of maximum normal stress on a bar as function of bar diameter, or radius, with a good display of information, and good coding fundamentals.
One can change the parameters to serve other purposes with the same type of graph, presentation.
The variables are deleted before the end except the ones required for graphing, to free up memory, as an example of clearvars.