Not all optimizers described in the namespace docstring are actually available

[lsolbach]

Optimizers like :bfgs are described in the namespace docstring but missing form the optimizers map.
Trying to use such an optimizer results in a "builder is null" error.

[genmeblog]

Thanks!
Be sure you're using current 3.0.0 alpha (snapshot) version and you look at 3.x branch.
:bfgs was defined in the past and relied on SMILE backend. Later I wrote own :lbfgsb implementation which reflects R/Fortran reference implementation and works pretty well.

I agree that documentation is vague (working on this).

Some examples:

(opt/minimize :lbfgsb (fn [x] (m/cos x)) {:bounds [[0 4]]})
;; => [(3.1415926535899494) -1.0]
(opt/maximize :lbfgsb (fn [x] (m/cos x)) {:bounds [[-1 2]]})
;; => [(6.206892834632102E-8) 0.9999999999999981]
(opt/minimize :lbfgsb (fn [x y] (m/* (m/sin x) (m/cos y))) {:bounds [[0 4] [0 4]]})
;; => [(1.5707960841212893 3.1415929226134973) -0.9999999999999344]
(opt/minimize :lbfgsb (fn [x y] (m/* (m/sin x) (m/cos y))) {:bounds [[0 4] [0 4]]
                                                           :stats? true})
;; => {:result
;;     [(1.5707960841212893 3.1415929226134973) -0.9999999999999344],
;;     :iterations 5,
;;     :gradient (-2.4267310383407903E-7 2.690236922120448E-7)}

;; using gradient
(opt/minimize :lbfgsb (fn [x] (m/sin x)) {:bounds [[0 6]] :gradient-f (fn [x] [(m/cos x)])})
;; => [(4.71238898038771) -1.0]