Ian HustonI am a theoretical cosmologist currently employed as a postdoctoral researcher in the Cosmology and Relativity group at Queen Mary, University of London.

Version 0.2.3 released

Posted by – May 22, 2012

Version 0.2.3 of Pyflation has been released and is available on the downloads page and via PyPI using pip install or easy_install.

This release fixes a major issue for multi-field models in which the nfields parameter would not be passed to model instances causing failure of model runs. The commit for the necessary change is viewable on Bitbucket.

Version 0.2.2 released

Posted by – May 3, 2012

I have just added the latest version of Pyflation to the Downloads page. Version 0.2.2 has minor improvements to the command line options for pyflation_firstorder and now includes the C files generated by Cython. Hopefully this means that installing from the Python Package Index will now work.


$ pip install pyflation


$ easy_install pyflation

to download and install from PyPi. You will need to have installed all the requirements beforehand.

The code for this update is also now available on the Bitbucket repository.

Git repository now available

Posted by – February 28, 2012

If you are a developer who would like to fork the Pyflation code, there is now a git repository available on Bitbucket. To clone the code to your local machine use:
$ git clone

The main branch of the code is available on the Bitbucket repository up until version 0.2.1. There is also an issue tracker if you have any problems to report.

Version 0.2.1 released

Posted by – February 16, 2012

The latest version of Pyflation is now available from the Downloads page and on the Python Package Index.

In this version there are many improvements in the documentation, and there are now docs available online.

Version 0.2 released

Posted by – November 30, 2011

A new version of Pyflation has been released! Get it from the Downloads page or right here.

Version 0.2.0 adds many new features including multi-field evolution of first order perturbations. Source term generation and therefore second order evolution are still only possible for single field models for now. Each model instance now has a nfields variable which is passed to the potential function. New two field and n-field potentials have been added to the cmpotentials module.

Another new feature is the analysis package which encapsulates functions to calculate power spectra of adiabatic and isocurvature perturbations and calculate the spectral indices for these quantities. This package features extensive unit test coverage (in the test directory) and has been used to create the results for a new submission to the arXiv.

Useful Python information for Astronomers

Posted by – May 25, 2011

A new course online course for astronomers who want to use Python has been set up by some researchers at the Harvard Center for Astrophysics. Practical Python for Astronomers describes how to get up and running with Python and is meant to be used as a hands on set of workshops.

Particularly interesting are the instructions for setting up a working Python, Numpy and Scipy environment using the Enthought Python Distribution, which is free for academic use. As these are the main requirements of Pyflation I have added a link to this important information on the installation page.

Beyond setting up the Python environment the course details how to plot images, read and write data from files and other useful tasks for astronomers. The course looks very worthwhile and the goal is that other groups undertake to provide their own workshops using this material as the basis. All the material is available under a Creative Commons Attribution License so that it is easy to adapt and modify the course to individual needs.

Paper now on the arXiv

Posted by – March 7, 2011

The paper accompanying the first release of the Pyflation package is now available on the arXiv preprint server. The tite and abstract of the paper are:

Second Order Perturbations During Inflation Beyond Slow-roll

Ian Huston, Karim A. Malik

We numerically calculate the evolution of second order cosmological perturbations for an inflationary scalar field without resorting to the slow-roll approximation or assuming large scales. In contrast to previous approaches we therefore use the full non-slow-roll source term for the second order Klein-Gordon equation which is valid on all scales. The numerical results are consistent with the ones obtained previously where slow-roll is a good approximation. We investigate the effect of localised features in the scalar field potential which break slow-roll for some portion of the evolution. The numerical package solving the second order Klein-Gordon equation has been released under an open source license and is available for download.

If you want to cite this paper the BiBTeX is

author         = “Huston, Ian and Malik, Karim A.”,
title          = “{Second Order Perturbations During Inflation Beyond
year           = “2011″,
eprint         = “1103.0912″,
archivePrefix  = “arXiv”,
primaryClass   = “astro-ph.CO”,
There are other versions of the bibliographic information available on the Inspire Beta listing.

Version 0.1.0 now available

Posted by – March 4, 2011

The first release of Pyflation is now available on the Downloads page. This is version 0.1.0 and coincides with the submission of our latest paper using Pyflation to the arXiv preprint repository.

Instructions for installing the package are available in the INSTALL.txt file and tips on usage are in the README.txt file.

Please remember that if you publish results obtained with Pyflation you are asked to cite one of the relevant publications.

New site

Posted by – February 15, 2011

This is the new site for Pyflation, a soon to be released Python package.

Pyflation numerically simulates an inflationary expansion of the universe using a single scalar field. Both first and second order perturbations are calculated, using the full non-slowroll equations of motion.