This patch implements code described in arXiv:1012.5299 and published in JCAP, with DOI 10.1088/1475-7516/2011/05/016. The patch applies to the January 2010 release of CosmoMC and is unlikely to work with more recent versions of CosmoMC. A more sophisticated interpolation algorithm is described in arXiv:1506.01079.


InterpMC is a patch for CosmoMC which speeds parameter estimation by caching the likelihoods computed as CosmoMC runs, fitting an interpolating polynomial and, when  feasible, using the interpolated values in place of a full likelihood computation.

To install InterpMC, download the unix patch file below, and a fresh copy of CosmoMC, then execute the following commands from the shell, in the CosmoMC source directory:

> patch –dry-run -p1 -i interp_mc.patch

[Checks patch will be applied without generating errors]

> patch -p1 -i interp_mc.patch

[Applies patch]

Then run “make” as usual.   Next, edit the params.ini file you are running with to include the following additional lines (possibly with other numerical values of your choice):

do_interp = T

interp_order = 4

factor = 3

cut = 8

faction_cut = 0.2

Now you can run CosmoMC as usual.

Click to download patch file.

Click to download ReadMe file.

InterpMC was written by Adam Bouland, Richard Easther and Katherine Rosenfeld.