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Development version

The development version contains changes that have not yet been tested well enough to be added to the main version. It has more features than numbered versions but you should also expect more bugs. See the development page for more details.

Version 1.4

Changes that may break existing workflows

  • The "like" values listed in the output chain files, which were always really posteriors all along, are now correctly labelled as such and so the column header has changed to "post".

Installation and compilation

  • Tweaks have been made to the recommended settings for manual compilation

CosmoSIS core changes

  • The output posteriors are now more correctly labelled as "post" (for log-posterior) rather than "like", since they include priors (thanks to Phil Marshall for discussion)
  • Various compiler flags have been tweaked
  • Fixes for El Capitan and additional compilers have been added to the core Makefiles (thanks to Anna Porredon for discussion).
  • The Gaussian likelihood now allows varying covariance and uses the log(det) term in that case. It also saves other useful info to the block.
  • Global sections visible to all modules can now be added in the pipeline.
  • Tools for and an example of scripting cosmosis from python have been added (Thanks to Michael Troxel for discussion).

Sampler changes

  • The experimental ABC sampler has been extended
  • The Fisher sampler can now include Gaussian priors as an additional matrix

## Demo changes - The demos have been updated to use the new modules described below

Postprocessing changes

  • Legends can now be added to plots made in postprocessing with command line flags
  • The postprocessor can now cope with final text file lines truncated when a job was killed
  • 1D curves and constraints from the Fisher sampler are now saved, as are ellipse areas for use as figures of merit.
  • The Grid samplers can now cope better with extreme likelihoods
  • Citations will not now be printed more than once

Standard Library Additions

  • The "project_2d" module in python replaces the old "spectra" module for projecting from 3D power spectra to 2D with the Limber approximation. It is now more consistent and complete, and respects the difference between matter power and galaxy power more clearly. It should be easier to extend to new spectra.
  • The 2pt_like module runs likelihoods on files in the new 2pt data format described at This makes it much easier to add new 2pt data sets.
  • The project_2d_ppf generates weak lensing spectra under parameterized deviations from GR that modify phi-psi
  • The load_nz_fits module loads n(z) (e.g. for photometric experiments) from the same file format as the 2pt_like module, or similar files.
  • Two new trivial bias modules have been added, for constant and unit bias
  • A planck2015_simple module has been added for forecasting purposes, which does a simple Gaussian likelihood for CMB data with Planck-sized errors. This is useful for forecasting but does not reflect real data.
  • A more general module for strong lensing time delay measurements has been added.

Standard Library Upgrades

  • Various new options are now exposed in CAMB, affecting kmax and accuracy levels (thanks to Vinicius Miranda).
  • Halofit will now take kmin and kmax from its linear power inputs by default
  • The sigmar module can now accept a single R or z value and should be slightly faster
  • The clerkin module can now accept a suffix to its output section
  • New options have been added to the intrinsic alignment modules. Several undocumented modules have also been added but we do not yet recommend their use.
  • New Alam 2015 data files have been packaged with the BOSS likelihood
  • The CFHTLenS and des-sv modules have been replaced with calls to the 2pt_like module described above.
  • The photoz_bias module can now work on multiple samples
  • Errors when running the Limber integral are more carefully reported
  • The defaults for the cl_to_xi_nicaea module are more sensible
  • The Planck Makefiles should now be easier to debug
  • The load_nz module can now save to any section using the wl_number_density section, aiding using multiple samples

Standard Library Fixes

  • A memory leak when running CAMB has been fixed
  • The ell_min has been changed in CLASS to make it match CAMB output
  • The Planck 2015 Makefile has been tweaked to reduce required environment variables
  • The output of Tinker mass function module has been fixed to allow proper output at z=0 only
  • Several pieces of units metadata in CAMB have been corrected (thanks to Vinicius Miranda)
  • Some details of the Tinker mass function have been corrected

Version 1.3


  • Fisher matrix sampler
  • New GaussianLikelihood superclass to help add Fisher-compatible Gaussian likelihoods

Standard Library Additions

  • Planck 2015 Likelihood
  • The Dark Energy Survey Science Verification Weak Lensing 2-point likelihood, including:
    • Photometric redshift bias marginalization
    • Shear bias marginalization
    • Power law intrinsic aligment models
    • xi(theta) likelihood
  • Add a utility to delete data block sections for more complex pipelines
  • Add matter and galaxy 2D C_ell spectra, and magnification, as well as their cross-correlations

Standard Library Updates

  • Allow extrapolate_power to work downwards to kmin as well as kmax
  • Allow switching off distance output in FrankenEmu
  • Modify several likelihoods to support Fisher matrices
  • Fix linking on OSX Yosemite

Standard Library Bug Fixes

  • Fix Planck Makefiles to work in Ubuntu - thanks to Matteo Costanzi
  • Fixed the "root" option
  • Improvement to customizability of various modules
  • Fix CAMB slowdown when P(k) not needed by exposing kmax parameter
  • Change how LAPACK is linked to enable easier custom linking
  • Fix a bug where the wrong values was used in BBN
  • Fix a compile error in the fgas module under newer gcc versions

Core Features

  • Lock output files when they are created to raise an error whey you accidentally leave out the --mpi flag or run two jobs with the same output file name.
  • Added a collection of physical constant values for use in modules (list taken from astropy.constants). In python: "import cosmosis.constants". In C: "#include cosmosis_constants.h". In Fortran: "#include cosmosis_constants.fh".
  • Save priors in the head of the output file
  • Allow the grid sampler to save its outputs progressively
  • Warn if more than 1 million grid points requested in the grid sampler
  • Enable saving chains in FITS format as well as text format


  • Enable adding extra derived parameters during postprocessing with user-defined functions
  • Add weighted MCMC scatter plots
  • Added lower and upper 95% limit statistics
  • Enable postprocessing importance samples
  • Enable plotting multiple different sampler outputs in one plot
  • Enable plotting only some of the chain parameters
  • Select whether you want transparent or opaque contours
  • Add scatter plot for weighted MCMC
  • Fix unusual factor of 100 appearing in some scatter plots
  • Add options to postprocess only a subset of 2D plots to save time
  • Fix a crash when plotting only one likelihood in P(k) test sampler plots (thanks to Tom McClintock)
  • Enable postprocessing FITS chains
  • Fix a bug when postprocessing PMC chains

Core Bug Fixes

  • Fix burning a fraction of the chain rather than a fixed number of samples when postprocessing
  • Fix a crash when one column was an exact linear function of another
  • Fix a bug that gave wrong MCMC median values

Version 1.2


  • Added Population Monte Carlo sampler
  • Added Snake grid sampler
  • Added Kombine ensemble sampler
  • Added List simple sampler
  • (Experimental) Enable making a graphical representation of a pipeline in the test sampler
  • Improved documentation pages of all the samplers


  • Add blinding option to post-processing
  • Enable postprocessing directory of cosmology results
  • Allow postprocessing MCMCs with weight columns
  • Fix which columns are plotted in post-processing
  • Add flag to swap x and y axes in plots

Standard Library Updates

  • Added MGCAMB
  • Added FrankenEmu Cosmic Emulator
  • Added Nicaea code for lensing C_ell -> xi(theta)
  • Added Lucy Clerkin bias code
  • Added Wrapper for CLASS Boltzmann code
  • Added Cluster f_gas likelihood by Adam Mantz
  • Added BBN YHe consistency module by Adam Mantz
  • Added Balmes-Corasaniti strong lensing likelihood
  • Added Suyu strong lensing likelihood
  • Added WiggleZ BAO likelihood
  • Updated to new version of isItGR
  • Added CAMB Jan 2015
  • Added a new format mode des_fmt to photo-z loader
  • Enable multiple renames in rename module
  • Enable using different consistency relation file in consistency module

Standard Library Bugs

  • Fixed linear alignment code
  • Fixed bug with covariance being wrong for CFHTLenS
  • Fixed error when z_min>0 in photo-z distributions
  • Fixed some compilation problems with Planck likelihood v1
  • Fix nan errors when A=0 in intrinsic alignments


  • Installer now works on Yosemite
  • Installer should be easier to update in future


  • Improve datablock logging facilities
  • Fix bugs with priors not working properly
  • Improved repository creation tool
  • Added an error reporting tool
  • Added a tool to download an existing module from a git/hg url
  • Added a tool to check for uncommitted changes

Version 1.1

There are two changes in v1.1 is that might break your runs:

  • you now should specify --mpi when running multinest in MPI mode
  • you may need to change some double parameters (like some of the planck nuisance params) from integers by adding .0 on the end

Standard library

  • Include small heliocentric correction to JLA supernova likelihood
  • Add isItGR modified gravity camb
  • Add newer Takahashi Halofit
  • Add module to log-linearly extrapolate matter power spectra
  • Add intrinsic aligments to weak lensing shear spectra
  • Add Linear Alignment model for intrinsic weak lensing alignments in several variants (Bridle & King, Bridle & King Corrected, and Kirk, Rassat, Host & Bridle)
  • Fix bugs stopping BBN likelihood from working at all
  • Add a PPF shear spectra calculation
  • Add utility functions to Limber approximation library
  • Increase accuracy of C_ell -> xi(theta) code
  • Add module that lets you sample in sigma_8 by re-scaling the output from CAMB.
  • Add mass functions from the CRL with numerical recipes replaced


  • Fix multinest MPI output problem where part of file overwritten
  • Enable saving data outputs in grid sampler
  • Fix bug saving additional output like sigma_8 from multinest
  • Let test sampler save as tgz output


  • Add new demos and split off longer demos into "examples" directory
  • Tweak amount of output in demo 6.
  • Use PLANCK_DATA_DIR environment variables in Planck demos
  • Demo 10: Smith Halofit versus Takahashi Halofit (plotting multiple ini files)
  • Demo 11: Modified gravity effect on shear spectra (grid sampling saved as tgz)
  • Demo 12: Extreme value stats for cluster masses
  • Example A: Old demo 10, moved.
  • Example B: Sample CFHTLenS with intrinsic aligments and sigma_8 (compare two models)
  • Example C: Multinest Planck (saving to sql?)


  • Allow environment variables in ini files
  • Update self-updater code to be able to checkout development version
  • Enable saving multiple 2D grids in Fortran
  • Enable saving datablocks to single tgz files
  • Fix saving/loading metadata after finishing the chain in text output files
  • Enable using environment variables in ini files
  • Enable integer parameters in values files being passed to pipelines


  • Fix plotting grid samples in cases with a very large range in likelihoods
  • Fix bug in Dunkley power spectrum testing printing repeated values
  • Stop grid plots from including 2D plots of likelihood versus parameter
  • Output all citations required by the pipeline

Version 1.0

Version 1.0 is the first fully released version of cosmosis.

If you have a module for a pre-release version then you may need to make minor changes to it. The main is that you may need to change how python modules import cosmosis features:

from cosmosis import names, option_section
from cosmosis.datablock import names, option_section

If you have developed module for the prototype des-pipe code then the interface functions have been changed significantly. See the documentation linked from the modules page for more information.