Trouble Accessing Minimizer from Optim

New to Julia
1

Hi All,

I am new to Julia and I am using the Optim package for the first time. The optimize function seems to be finding a solution to my problem, but I cannot figure out how to access the solution. All I see is the objective value. The Optim documentation states that the result object should have a “minimizer” field, but whenever I try to access this field, I get an error that “minimizer is not defined”. Any help would be greatly appreciated. I am guessing there is a very simple answer, but I have not been able to figure it out. Thanks!

  • Status: success

  • Candidate solution
    Final objective value: -1.647806e+00

  • Found with
    Algorithm: Fminbox with L-BFGS

  • Convergence measures
    |x - x’| = 9.51e-07 ≰ 0.0e+00
    |x - x’|/|x’| = 3.03e-06 ≰ 0.0e+00
    |f(x) - f(x’)| = 0.00e+00 ≤ 0.0e+00
    |f(x) - f(x’)|/|f(x’)| = 0.00e+00 ≤ 0.0e+00
    |g(x)| = 8.43e-10 ≤ 1.0e-08

  • Work counters
    Seconds run: 0 (vs limit Inf)
    Iterations: 3
    f(x) calls: 23
    ∇f(x) calls: 23

2

Can you show what you have actually done to get the error? Because this works:

julia> using Optim

julia> rosenbrock(x) =  (1.0 - x[1])^2 + 100.0 * (x[2] - x[1]^2)^2
rosenbrock (generic function with 1 method)

julia> result = optimize(rosenbrock, zeros(2), BFGS())
 * Status: success
(...)

julia> result.minimizer
2-element Vector{Float64}:
 0.9999999926033423
 0.9999999852005353
1 Like
3

Hi, it is working now. I am not sure what I was doing wrong before. Thanks!

1 Like