scipy/scipy — comment on commit 2570a3b685fdc45e0bc5d00f27e71ba78993efad
File: scipy/optimize/lbfgsb.py line 153
By pv:

Which raises the question whether the optimizers should cache the results from function evaluation internally, or leave this to the user. Doing this with a memoizing wrapper that remembers the result at the previous point probably wouldn't be too difficult to add.