Midpoint Rule for finding the area under a curve.

Midpoint rule says to multiply the delta-x {(b-a)/n} by the sum of the Function_result at each midpoint of each interval.  
Example:  Find the area under the curve of x^2, from 0 to 4 with 8 divisions.
delta-x = (4-0)/8 = 1/2
midpoint rule = (1/2)(1/16+9/16+25/16+49/16+81/16+121/16+169/16+225/16)=21.25
If the numbers in the second set of parentheses look weird, it's because they are 
the Function Result (x^2) of each of the midpoints on each interval.

When the program is run, L=left boundry, R=right boundry and N=number of divisions.