What is PICO?

PICO is an algorithm that quickly computes the CMB scalar, tensor and lensed power spectra, and the matter transfer function. It is intended to accelerate parameter estimation codes. More generally, PICO allows using massively parallel computing resources, including distributed computing projects such as Cosmology@Home, to speed up the slow steps in inherently sequential calculations.

PICO is described in detail in W. A. Fendt and B. D. Wandelt, astro-ph/0606709. Improvements to the algorithm as well as results for a nonflat model are presented in astro-ph/0712.0194


  • Compute the CMB power spectrum and matter transfer function
  • Sufficient accuracy for parameter estimation from Planck or SPT data.
  • Python wrapper
  • Built-in CosmoMC plugin

Comparison of posteriors using PICO and CAMB

Red line uses CAMB and WMAP software (1.5 weeks).
Green line uses Pico and WMAP software (4 hours).
Blue line uses only Pico (1.5 hours).
The 2D plots show the 68% and 99% contours.

Precision of Power Spectra Computed by PICO

Red line is the mean error over the test set.
Blue line is the 99% error bars over the test set.
Power spectrum error is plotted in units of cosmic standard deviation.
Matter transfer function error is plotted as percent error.