Is it possible to use Newton() methods with limiting some variables? Like FMinbox?
please start with the manual, eg
Thank you, I read the manual. I think I know how Fminbox() works, but it doesn’t work with Newton(). (L)BFGS() works fine with Fminbox(), but I hope to have some solution for Newton().
See this issue you may be running into, and particularly this comment:
https://github.com/JuliaNLSolvers/Optim.jl/issues/600#issuecomment-420946414
Thanks, i will try!
Thanks, this issue is wery close to my project. I also need to maximize likelihood function and one of parameter of covariance matrix - rho - changing in limits 0 - 1.0, and when i use LBFGS - it’s works fine, but to slow. Newton() works fast, but i need to do things like this: if rho > 1 rho = 1 end and this is not good, because last step of optimization some time > 1.0 end it can leads to “stuck” in value 1.0 when real value close to 1.0 ( f.e. 0.988). I try to use “link function” like sigmoid, but at marginal values it works not good: 1/(1+exp(x)) not works correctly, 1/(1+x^4) works nearly good, but not not better when rho “force limited”. Now i use LBFGS till rho is stable and then use Newton(), or Newton() at first step and then LBFGS, but i think there must be a better way.
It is hard to say more about this without an MWE (eg do you provide derivatives manually or use AD, what is rho [stepsize correction?], …).
Hi! I use AD, and likelihood function based on derivation of variance-covariance matrix. For example 2x2 matrix (ρ, σ₁, σ₂ - should be found)
σ²₁ ρσ₁σ₂
ρσ₁σ₂ σ²₂
where ρ covariation coefficient that should be also found - and it can be in the range 0 - 1.
You might have better luck transforming your variables, as done here: Optim.jl . They work with the log variance which can take on any value. For ρ you could use tanh and atanh to go back and forth between (-1, 1) and (-inf, inf)
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