Computation times

00:01.891 total execution time for 3 files from examples/optimization_problem:

Example	Time	Mem (MB)
Analytical test case # 2 (plot_simple_opt_2.py)	00:01.100	0.0
Analytical test case # 3 (plot_simple_opt_3.py)	00:00.789	0.0
Analytical test case # 1 (plot_simple_opt_1.py)	00:00.003	0.0