Poisson's equation for the 1s state of hydrogen

For Problem 2.3 (of HW#2), make a plot which shows both your solution ( vs. r(u)) and the analytic formula

Also, so that we can investigate convergence, make sure your code

• takes Nu as input from the keyboard for values up to 100,000; and
• prints out the value of ( ) as computed at the origin (r=0) to at least 15 digits (C: ``%20.15f''; Fortran: ``f20.15'').