Doc example with complex numbers not working

[luigiannelli]

the example at page https://julianlsolvers.github.io/Optim.jl/stable/#algo/complex/ fails.
the environment is:

• julia 1.1.1
• IJulia v1.20.2
• Optim v0.20.0

minimal (not) working example from the docs of the page linked above:

using Random, LinearAlgebra, Optim
Random.seed!(0) # Set the seed for reproducibility
# μ is the strength of the quartic. μ = 0 is just a quadratic problem
n = 4
A = randn(n,n) + im*randn(n,n)
A = A'A + I
b = randn(n) + im*randn(n)
μ = 1.0

fcomplex(x) = real(dot(x,A*x)/2 - dot(b,x)) + μ*sum(abs.(x).^4)
gcomplex(x) = A*x-b + 4μ*(abs.(x).^2).*x
gcomplex!(stor,x) = copyto!(stor,gcomplex(x))

x0 = randn(n)+im*randn(n)

res = optimize(fcomplex, gcomplex!, x0, LBFGS())

output:

MethodError: no method matching ini_dec(::Complex{Float64}, ::Int64, ::Array{UInt8,1})
Closest candidates are:
  ini_dec(::Any, ::Any, !Matched::Int64, !Matched::String, !Matched::Int64, !Matched::Int64, !Matched::Char, !Matched::Any) at printf.jl:842
  ini_dec(!Matched::BigInt, ::Int64, ::Any) at printf.jl:1053
  ini_dec(!Matched::Integer, ::Int64, ::Any) at printf.jl:1011
  ...

Stacktrace:
 [1] ini_dec(::Base.GenericIOBuffer{Array{UInt8,1}}, ::Complex{Float64}, ::Int64, ::String, ::Int64, ::Int64, ::Char, ::Array{UInt8,1}) at ./printf.jl:842
 [2] (::getfield(Optim, Symbol("##2#4")))(::Complex{Float64}) at ./printf.jl:0
 [3] iterate at ./generator.jl:47 [inlined]
 [4] collect(::Base.Generator{Base.Iterators.Take{Array{Complex{Float64},1}},getfield(Optim, Symbol("##2#4"))}) at ./array.jl:606
 [5] show(::IOContext{Base.GenericIOBuffer{Array{UInt8,1}}}, ::Optim.MultivariateOptimizationResults{LBFGS{Nothing,LineSearches.InitialStatic{Float64},LineSearches.HagerZhang{Float64,Base.RefValue{Bool}},getfield(Optim, Symbol("##19#21"))},Float64,Array{Complex{Float64},1},Float64,Float64,Array{OptimizationState{Float64,LBFGS{Nothing,LineSearches.InitialStatic{Float64},LineSearches.HagerZhang{Float64,Base.RefValue{Bool}},getfield(Optim, Symbol("##19#21"))}},1},Bool}) at /home/luigi/.julia/packages/Optim/Q2XsG/src/types.jl:242
 [6] show at ./sysimg.jl:219 [inlined]
 [7] limitstringmime(::MIME{Symbol("text/plain")}, ::Optim.MultivariateOptimizationResults{LBFGS{Nothing,LineSearches.InitialStatic{Float64},LineSearches.HagerZhang{Float64,Base.RefValue{Bool}},getfield(Optim, Symbol("##19#21"))},Float64,Array{Complex{Float64},1},Float64,Float64,Array{OptimizationState{Float64,LBFGS{Nothing,LineSearches.InitialStatic{Float64},LineSearches.HagerZhang{Float64,Base.RefValue{Bool}},getfield(Optim, Symbol("##19#21"))}},1},Bool}) at /home/luigi/.julia/packages/IJulia/F1GUo/src/inline.jl:43
 [8] display_mimestring(::MIME{Symbol("text/plain")}, ::Optim.MultivariateOptimizationResults{LBFGS{Nothing,LineSearches.InitialStatic{Float64},LineSearches.HagerZhang{Float64,Base.RefValue{Bool}},getfield(Optim, Symbol("##19#21"))},Float64,Array{Complex{Float64},1},Float64,Float64,Array{OptimizationState{Float64,LBFGS{Nothing,LineSearches.InitialStatic{Float64},LineSearches.HagerZhang{Float64,Base.RefValue{Bool}},getfield(Optim, Symbol("##19#21"))}},1},Bool}) at /home/luigi/.julia/packages/IJulia/F1GUo/src/display.jl:67
 [9] display_dict(::Optim.MultivariateOptimizationResults{LBFGS{Nothing,LineSearches.InitialStatic{Float64},LineSearches.HagerZhang{Float64,Base.RefValue{Bool}},getfield(Optim, Symbol("##19#21"))},Float64,Array{Complex{Float64},1},Float64,Float64,Array{OptimizationState{Float64,LBFGS{Nothing,LineSearches.InitialStatic{Float64},LineSearches.HagerZhang{Float64,Base.RefValue{Bool}},getfield(Optim, Symbol("##19#21"))}},1},Bool}) at /home/luigi/.julia/packages/IJulia/F1GUo/src/display.jl:96
 [10] #invokelatest#1 at ./essentials.jl:742 [inlined]
 [11] invokelatest at ./essentials.jl:741 [inlined]
 [12] execute_request(::ZMQ.Socket, ::IJulia.Msg) at /home/luigi/.julia/packages/IJulia/F1GUo/src/execute_request.jl:112
 [13] #invokelatest#1 at ./essentials.jl:742 [inlined]
 [14] invokelatest at ./essentials.jl:741 [inlined]
 [15] eventloop(::ZMQ.Socket) at /home/luigi/.julia/packages/IJulia/F1GUo/src/eventloop.jl:8
 [16] (::getfield(IJulia, Symbol("##15#18")))() at ./task.jl:259

[antoine-levitt]

JuliaNLSolvers/NLSolversBase.jl#117 maybe? Does JuliaNLSolvers/NLSolversBase.jl#118 fix it?

[luigiannelli]

It's not a problem for me, i just wrote the code for Real variables, but it's not good that a Doc example does not work.

[pkofod]

This is point 1 of #775

[pkofod]

Fixed on the latest release

julia> res = optimize(fcomplex, gcomplex!, x0, LBFGS())
 * Status: success

 * Candidate solution
    Final objective value:     -1.706873e+00

 * Found with
    Algorithm:     L-BFGS

 * Convergence measures
    |x - x'|               = 4.23e-09 ≰ 0.0e+00
    |x - x'|/|x'|          = 6.91e-09 ≰ 0.0e+00
    |f(x) - f(x')|         = 2.22e-16 ≰ 0.0e+00
    |f(x) - f(x')|/|f(x')| = 1.30e-16 ≰ 0.0e+00
    |g(x)|                 = 1.23e-10 ≤ 1.0e-08

 * Work counters
    Seconds run:   0  (vs limit Inf)
    Iterations:    15
    f(x) calls:    44
    ∇f(x) calls:   44