CosmoCoffee

Dear Antony,
I am using the June 2016 version of Cosmomc and running using mock data with default paramteres. The mock data was generated using the makePerfectForecastDataset.py code with the Cl's output from CAMB. For some reason the Monte Carlo does not start and I get the following error:

starting Monte-Carlo
Matrix_Cholesky: not positive definite 2
MpiStop: 23
application called MPI_Abort(MPI_COMM_WORLD, 1) - process 23

I read up similar posts on Cosmocoffee where the issue was resolved by deleting the *.chk checkpoint files. However in my case, I have disabled checkpointing and hence there are no .chk files.

Any idea about what I could be doing wrong?

A problem with your propose matrix?

Not sure... I am using defaults.

So I gave a run of cosmomc with input dataset being the Cl's(TT) obtained from CMB sky simulation(based on Planck LCDM parameter values). I have used propose matrix= run.covmat generated from the previous run with the same parameters. At the end of the run, my R-1 value was 0.0011. When I use Getdist to analyse the chains, I notice that there is no proper "peak" in the Tau plot. Could you tell what is going wrong?
The range set for Tau in batch2/params_CMB_defaults.ini is: param[tau] = 0.09 0.01 0.8 0.01 0.005

I am attaching the Tau plot here.

/cosmo_files.php?file=joby_pk/tau.jpg

Perhaps your simulated data had tau value of 0? (so cut off by the 0.01 minimum). There doesn't have to be a peak away from the boundary.