Hi,

I am trying to perform a function minimization with BigFloat numbers. However, it seems that I cannot get it to work. I am using the BlackBoxOptim.jl package.

Is there a way to do that? As an example, I tried to do it with the Rosenbrock function.

```
function rosenbrock2d(x)
return (1 - x[1])^2 + 100 * (x[2] - x[1]^2)^2
end
res = bboptimize(rosenbrock2d; SearchRange = [(-BigFloat(5//3),BigFloat(5//3)),(-BigFloat(5//3),BigFloat(5//3))])
```

This works, but the result is a Float64.

If I do

```
function rosenbrock2d(x)
return BigFloat((1 - x[1])^2 + 100 * (x[2] - x[1]^2)^2)
end
res = bboptimize(rosenbrock2d; SearchRange = [(-BigFloat(5//3),BigFloat(5//3)),(-BigFloat(5//3),BigFloat(5//3))])
```

instead, I get the following error

```
ArgumentError: The supplied fitness function does NOT return the expected fitness type Float64when called with a potential solution (when called with [0.6116625671601585, -1.6325667883503008] it returned 402.83444589341110031455173157155513763427734375 of type BigFloat so we cannot optimize it!
Stacktrace:
[1] setup_problem(func::Function, parameters::ParamsDictChain)
@ BlackBoxOptim ~/.julia/packages/BlackBoxOptim/I3lfp/src/bboptimize.jl:40
[2] bbsetup(functionOrProblem::Function, parameters::Dict{Symbol, Any}; kwargs::Base.Pairs{Symbol, Vector{Tuple{BigFloat, BigFloat}}, Tuple{Symbol}, NamedTuple{(:SearchRange,), Tuple{Vector{Tuple{BigFloat, BigFloat}}}}})
@ BlackBoxOptim ~/.julia/packages/BlackBoxOptim/I3lfp/src/bboptimize.jl:111
[3] bboptimize(functionOrProblem::Function, parameters::Dict{Symbol, Any}; kwargs::Base.Pairs{Symbol, Vector{Tuple{BigFloat, BigFloat}}, Tuple{Symbol}, NamedTuple{(:SearchRange,), Tuple{Vector{Tuple{BigFloat, BigFloat}}}}})
@ BlackBoxOptim ~/.julia/packages/BlackBoxOptim/I3lfp/src/bboptimize.jl:92
[4] top-level scope
@ In[62]:1
[5] eval
@ ./boot.jl:368 [inlined]
[6] include_string(mapexpr::typeof(REPL.softscope), mod::Module, code::String, filename::String)
@ Base ./loading.jl:1428
```

How can I solve? In case, I would be very glad if you could point me to other global optimization techniques too that allow me to use BigFloats.

Thanks a lot!