Rosenbrock's function in 100 dimensions, from (-1.2, 1, -1.2, 1, ...) where f = 24926
L-BFGS-B with 10 pairs to f <= 1e-10: the analytic gradient, and forward differences
       analytic gradient        forward differences
round  evaluations  best value  evaluations  best value
    0            1       2.5e4          101       2.5e4
   50           51       9.3e1         5151       9.3e1
  100          101       8.3e1        10201       8.3e1
  150          151       7.4e1        15251       7.4e1
  200          201       6.5e1        20301       6.5e1
  250          251       5.7e1        25351       5.7e1
  300          301       4.8e1        30401       4.8e1
  350          351       4.0e1        35451       3.9e1
  400          401       3.2e1        40501       3.0e1
  450          451       2.3e1        45551       2.1e1
  500          501       1.4e1        50601       1.3e1
  550          551       5.7e0        55651       3.5e0
  600          601      3.3e-5        60701      5.3e-9
  605          606      1.9e-7        61206     9.9e-11
  612          613     3.0e-11                         
analytic gradient: f = 3.0e-11 after 520 iterations and 613 evaluations
forward differences: f = 9.9e-11 after 523 iterations and 61206 evaluations
forward differences took 100 times the evaluations
