CosmoCoffee Forum Index CosmoCoffee

 
 FAQFAQ   SearchSearch  MemberlistSmartFeed   MemberlistMemberlist    RegisterRegister 
   ProfileProfile   Log inLog in 
Arxiv New Filter | Bookmarks & clubs | Arxiv ref/author:

CosmoMC: finding max like point
 
Post new topic   Reply to topic    CosmoCoffee Forum Index -> Computers and software
View previous topic :: View next topic  
Author Message
Davide Maino



Joined: 22 Sep 2005
Posts: 11
Affiliation: Physics Dept., University of Milano

PostPosted: September 06 2006  Reply with quote

Hi Anthony,
I'm trying to run CosmoMC with all_exact_l and set estimate_propose_matrix = T. After a while the code exits with and error

ERROR: Trial parameters excluded by prior or error in likelihood
Try starting further away from problem regions?

I have two questions:
1. how can I solve the problem?
2. Wouldn't it be nice to have indication from the code which is the parameters that causes the error?

Thanks a lot,

- Davide.
Back to top
View user's profile [ Hidden ]
Antony Lewis



Joined: 23 Sep 2004
Posts: 876
Affiliation: University of Sussex

PostPosted: September 07 2006  Reply with quote

I never use this option myself.. as people have seen it is not very reliable, especially with parameters with priors. If anyone wants to improve it I'd be happy to incorporate improvements...

btw, someone found a bug in August 2006 CosmoMC version with tensor modes. I updated the download today.
Back to top
View user's profile [ Hidden ] Visit poster's website
Davide Maino



Joined: 22 Sep 2005
Posts: 11
Affiliation: Physics Dept., University of Milano

PostPosted: September 07 2006  Reply with quote

Hi Anthony,
thanks for the prompt answer. I'll download the new version when ready.
So you suggest me not to use the option and let things go by themselves.

I'm quite new to these issues but given the nature of the simulations
would it be faster to first get an idea of the propose_matrix so that the
MCMC part would better concentrate on the right parameter space region?

Ciao,


- Davide.
Back to top
View user's profile [ Hidden ]
Antony Lewis



Joined: 23 Sep 2004
Posts: 876
Affiliation: University of Sussex

PostPosted: September 07 2006  Reply with quote

If you can get some propose_matrix estimate that will help. But if you don't have one the learn_propose option usually works quite well with sensible input parameters (and is a lot more robust that the estimate_propose_matrix option).
Back to top
View user's profile [ Hidden ] Visit poster's website
Davide Maino



Joined: 22 Sep 2005
Posts: 11
Affiliation: Physics Dept., University of Milano

PostPosted: September 07 2006  Reply with quote

OK. Fine for me.
Ciao,


- Davide.
Back to top
View user's profile [ Hidden ]
Jie Ren



Joined: 13 May 2006
Posts: 28
Affiliation: Theoretical Physics Division, Chern Institute of Mathematics, Nankai University, Tianjin, China

PostPosted: September 23 2006  Reply with quote

I do not know how to solve the following problem about propose matrix. Thanks a lot for any helps!

In CosmoMC Readme,
*****************************************
If you don't have a propose_matrix, set estimate_propose_matrix = T to automatically esimate it by numerical differentiation about the best fit point. To use this option you should not have parameter priors cutting off the distribution near the maximum likelihood.
*****************************************

When I set estimate_propose_matrix=T and run, why does this error occur:

[root@localhost cosmomc]# ./cosmomc params.ini
Random seeds: 22217, 28465 rand_inst: 0
Cannot have estimate_propose_matrix and propose_matrix
[root@localhost cosmomc]#

And what is the meaning of the matrix in params_CMB.covmat? If one adds some parameters, how can one deal with the problem of propose matrix?
Back to top
View user's profile  
Jie Ren



Joined: 13 May 2006
Posts: 28
Affiliation: Theoretical Physics Division, Chern Institute of Mathematics, Nankai University, Tianjin, China

PostPosted: September 24 2006  Reply with quote

I have known that this error is due to that the line "propose_matrix = params_CMB.covmat" should be commented when one sets "estimate_propose_matrix = T".
Back to top
View user's profile  
Sarah Bridle



Joined: 24 Sep 2004
Posts: 147
Affiliation: University College London (UCL)

PostPosted: September 29 2006  Reply with quote

Is the error solved on commenting out the line
"propose_matrix = params_CMB.covmat"
?
Back to top
View user's profile   Visit poster's website
Jie Ren



Joined: 13 May 2006
Posts: 28
Affiliation: Theoretical Physics Division, Chern Institute of Mathematics, Nankai University, Tianjin, China

PostPosted: September 29 2006  Reply with quote

Commenting the line "propose_matrix = params_CMB.covmat" seems equal to modify it as "propose_matrix = ". If one adds parameters and also uses "propose_matrix = params_CMB.covmat", this error will occur. Sometimes, this error is due to not running "make clean" after one modifies some files of the program.
Back to top
View user's profile  
Antony Lewis



Joined: 23 Sep 2004
Posts: 876
Affiliation: University of Sussex

PostPosted: October 05 2012  Reply with quote

As of the Oct 2012 version, best-fit finding (action=2) and estimate_propose_matrix should work more reliably, esp. with parameters that have hard prior cuts.
Back to top
View user's profile [ Hidden ] Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    CosmoCoffee Forum Index -> Computers and software All times are GMT + 5 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group. Sponsored by WordWeb online dictionary and dictionary software.