### CosmoMC: Finding the best fit Log likelihood

Posted:

**October 26 2005**Dear all:

I want to find the best fit -Log(Like) value of a given cosmological model using some datasets.I set action = 2 in params.ini since MCMC cannot provide accurate best fit values. Testing with \Lambda CDM model using WMAP-only data , I found the same result using two different initial seeds as follows:

Random seeds: 4321, 9373 rand_inst: 0

Random seeds: 12345, 9373 rand_inst: 0

Computing tensors: F

Doing CMB lensing: F

lmax = 2100

Number of C_ls = 3

Varying 6 parameters ( 2 fast)

reading: params_CMB.covmat

Finding max-like point

reading WMAP data

WMAP read

Change in F is less than 0.10000000 after 4 iterations

Found minimum value of -Log(Like) = 717.2668

Converged sucessfully (loglike changes by less than 0.1000000 )

after 4 iterations

Best fit parameters values:

1 : 2.3866521E-02

2 : 0.1122643

3 : 1.049735

4 : 0.1119891

8 : 0.9966581

11 : 3.118499

Have estimated the minimum, now exiting since action=2

Wrote the minimum to file chains/test2.minimum

I used all the default setting in params.ini except

action=2

delta_loglike = 0.1

use_CMB = T

use_HST = F

use_mpk = F

use_clusters = F

use_BBN = F

use_Age_Tophat_Prior = F

use_SN = F

use_min_zre = 0

The best-fit -Log(Like)=717.2668 is larger than the other published fitting results ( around 714 ),I have tested by setting delta_loglike = 1,2 ,the best-fit -Log(Like) got larger. Did I make any mistakes ? Any comments and suggestion on that ?

Thanks in advance .

Cheers

Gongbo Zhao

I want to find the best fit -Log(Like) value of a given cosmological model using some datasets.I set action = 2 in params.ini since MCMC cannot provide accurate best fit values. Testing with \Lambda CDM model using WMAP-only data , I found the same result using two different initial seeds as follows:

Random seeds: 4321, 9373 rand_inst: 0

Random seeds: 12345, 9373 rand_inst: 0

Computing tensors: F

Doing CMB lensing: F

lmax = 2100

Number of C_ls = 3

Varying 6 parameters ( 2 fast)

reading: params_CMB.covmat

Finding max-like point

reading WMAP data

WMAP read

Change in F is less than 0.10000000 after 4 iterations

Found minimum value of -Log(Like) = 717.2668

Converged sucessfully (loglike changes by less than 0.1000000 )

after 4 iterations

Best fit parameters values:

1 : 2.3866521E-02

2 : 0.1122643

3 : 1.049735

4 : 0.1119891

8 : 0.9966581

11 : 3.118499

Have estimated the minimum, now exiting since action=2

Wrote the minimum to file chains/test2.minimum

I used all the default setting in params.ini except

action=2

delta_loglike = 0.1

use_CMB = T

use_HST = F

use_mpk = F

use_clusters = F

use_BBN = F

use_Age_Tophat_Prior = F

use_SN = F

use_min_zre = 0

The best-fit -Log(Like)=717.2668 is larger than the other published fitting results ( around 714 ),I have tested by setting delta_loglike = 1,2 ,the best-fit -Log(Like) got larger. Did I make any mistakes ? Any comments and suggestion on that ?

Thanks in advance .

Cheers

Gongbo Zhao