Code for Anisotropies in the Microwave Background

cosmology, CAMB, CMB, 21cm-signal, cosmic-microwave-background, gravitational-lensing, large-scale-structure, python-package
pip install camb==1.5.5



CAMB: Code for Anisotropies in the Microwave Background
Author: Antony Lewis and Anthony Challinor

Description and installation

CAMB is a cosmology code for calculating cosmological observables, including CMB, lensing, source count and 21cm angular power spectra, matter power spectra, transfer functions and background evolution. The code is in Python, with numerical code implemented in fast modern Fortran.

See the CAMB python example notebook for a quick introduction to how to use the CAMB Python package.

For a standard non-editable installation use:

pip install camb [--user]

The --user is optional and only required if you don't have write permission to your main python installation. To install from source, clone from github using:

git clone --recursive

Then install using:

pip install -e ./CAMB [--user]

You will need gfortran 6 or higher installed to compile (usually included with gcc by default). If you have gfortran installed, "python make" (and other standard setup commands) will build the Fortran library on all systems (including Windows without directly using a Makefile).

The python wrapper provides a module called "camb" documented in the Python CAMB documentation.

After installation you can also run CAMB from the command line reading parameters from a .ini file, e.g.:

camb inifiles/planck_2018.ini

To compile the Fortran command-line code run "make camb" in the fortran directory. For full details see the ReadMe.


The master branch contains latest changes to the main release version.

The devel branch contains latest less-stable things in development. The master and devel branches have an integrated test suite, which runs automatically on Travis for new commits and pull requests. Reference results and test outputs are stored in the test outputs repository. Tests can also be run locally.

To reproduce legacy results, see these branches:

  • CAMB_sources is the old public CAMB Sources code.
  • CAMB_v0 is the old Fortran-oriented (gfortran 4.8-compatible) version as used by the Planck 2018 analysis.
  • rayleigh includes frequency-dependent Rayleigh scattering
  • python2 is the last Python 2 compatible version