## Cobaya minimizer question

Use of Cobaya. camb, CLASS, cosmomc, compilers, etc.
Helena Garcia
Posts: 10
Joined: October 05 2021
Affiliation: UCI

### Cobaya minimizer question

I want to run minimization over the calculated chains using mcmc with cobaya and I don't know where you I write the path of the chains so that the program can use them to do a more precise minimazation? Thanks!

Antony Lewis
Posts: 1765
Joined: September 23 2004
Affiliation: University of Sussex
Contact:

### Re: Cobaya minimizer question

You need to do a minimization run to find a minimum, you can't find a global minimum from chains since in high dimensions there are almost no samples near the posterior peak.

Helena Garcia
Posts: 10
Joined: October 05 2021
Affiliation: UCI

### Re: Cobaya minimizer question

I am running nested models, for example, LCDM and the LCDM + w free, therefore, I'm expecting a better fit for the model that has more freedom (in this case LCDM+w. Nevertheless, when I run minimizer over this two models, I get a smaller minuslogpost (in absolute magnitude) for the LCDM than for the LCDM + w free, which is mathematically inconsistent. I have ran the full chains since I thought it was necessary in order to run the minimizer.

How I set up the minimizer run is by changing the last part in the .yaml file (instead of mcmc sampler):

Code: Select all

sampler:
minimize:
method: bobyqa
ignore_prior: False
max_evals: 1e6d
best_of: 2
confidence_for_unbounded: 0.9999995

Is this the way to proceed or am I doing something wrong? How should one set this run?