"Everything should be made as SIMPLE as possible, but no simpler"
Single-particle IMage Processing Linux Engine (SIMPLE 2.0) does ab initio 3D reconstruction, heterogeneity analysis, and refinement (programs simple_cluster, simple_origami, simple_softmatch, simple_reconstruct, and simple_automask). The SIMPLE 2.0 back-end consists of an object-oriented numerical library with a single external dependency—the Fastest Fourier Transform in the West (FFTW). The SIMPLE 1.0 front-end consists of a few standalone, interoperable components developed according to the 'Unix toolkit philosophy'. SIMPLE 2.0 is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the license, or (at your option) any later version. SIMPLE 2.0 is distributed with the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.
SIMPLE 1.0 can be found here.
SIMPLE 2.1 can be found here.