#RELION

RELION (for REgularised LIkelihood OptimisatioN) is a stand-alone computer program for Maximum A Posteriori refinement of (multiple) 3D reconstructions or 2D class averages in cryo-electron microscopy. It is developed in the research group of Sjors Scheres at the MRC Laboratory of Molecular Biology.

The underlying theory of MAP refinement is given in a scientific publication . If RELION is useful in your work, please cite this paper.

The more comprehensive documentation of RELION is stored on the Wiki

##Installation

More extensive options and configurations are available here, but the outlines to clone and install relion for typical use are made easy through cmake.

On ubuntu machines, installing cmake is as easy as

sudo apt install cmake

On other systems it is typically just as easy, you simply have to modify "apt" to the appropriate package manager. You will also need git, which is just as easy;

sudo apt install git

Once git and cmake are installed, relion can be easily installed through

git clone https://github.com/3dem/relion.git
cd relion
mkdir build
cd build
cmake -DCMAKE_INSTALL_PREFIX=/where/to/install/ ..
make -j4
make install

These steps will download the source-code, create a build-directory, then configure and build relion, and lastely install it to be generally available on the system.

##Updating

RELION is intermittently updated, with both minor and major features. To update an existing installation, simply use the following commands

cd relion/build
git pull
make -j4
make