Robert,
your first expression is really
julia> -(0.11292333772901704 ^ 1.0000060554544523)
-(0.11292333772901704 ^ 1.0000060554544523)
while the second one changes it to
julia> (-0.11292333772901704) ^ 1.0000060554544523
ERROR: DomainError
in ^ at math.jl:252
which is indeed mathematically undefined.
On Tuesday, August 12, 2014 2:24:39 PM UTC+2, Robert Feldt wrote:
>
> Actually this might be a bug. I really don't understand this behavior
> (latest 0.3.0-rc3):
>
> feldt:~/tmp$ julia03
> _
> _ _ _(_)_ | A fresh approach to technical computing
> (_) | (_) (_) | Documentation: http://docs.julialang.org
> _ _ _| |_ __ _ | Type "help()" for help.
> | | | | | | |/ _` | |
> | | |_| | | | (_| | | Version 0.3.0-rc3 (2014-08-10 02:54 UTC)
> _/ |\__'_|_|_|\__'_| | Official http://julialang.org/ release
> |__/ | x86_64-apple-darwin13.3.0
>
> julia> -0.11292333772901704 ^ 1.0000060554544523
> -0.11292184633488864
>
> julia> x = -0.11292333772901704
> -0.11292333772901704
>
> julia> p = 1.0000060554544523
> 1.0000060554544523
>
> julia> x ^ p
> ERROR: DomainError
> in ^ at math.jl:252
>
>
>
> Den tisdagen den 12:e augusti 2014 kl. 14:04:58 UTC+2 skrev Robert Feldt:
>>
>> Can LsqFit.jl be used to fit multivariate model? I tried this but must
>> have missed something (maybe xv and Y need to have same length?):
>>
>> using LsqFit
>>
>> # We want to try to use curve_fit to fit the parameters of this
>> multivariate model:
>> mvmodel(x, p) = begin
>> p[1] .* ((x[1,:] .^ p[2]) ./ (x[2,:] .^ p[3]))
>> end
>> N = 10
>> M = 2
>> X = randn(M, N)
>> Params = [1.0, 2.0, 2.0] # Actual params that we are looking for
>>
>> # Dependent var with small error term
>> Y = mvmodel(X, Params)[:] + 0.01*randn(N)
>>
>> # We need a vector to submit to curve_fit:
>> xv = X[:]
>>
>> # Reshape to get back the original matrix.
>> orig_matrix(xv, M) = reshape(xv, (M, int(length(xv)/M)))
>>
>> # The model function we supply to curve_fit needs to take a vector...
>> model(xv, p) = mvmodel(orig_matrix(xv, M), p)
>>
>> fit = curve_fit(model, xv, Y, [0.5, 0.5, 0.5])
>>
>>
>> Den måndagen den 14:e juli 2014 kl. 20:10:02 UTC+2 skrev Blake Johnson:
>>>
>>> The curve fitting functionality in Optim.jl is being moved into its own
>>> package: LsqFit.jl:
>>>
>>> https://github.com/JuliaOpt/LsqFit.jl
>>>
>>> Installable via Pkg.add("LsqFit").
>>>
>>
