.. _makingModules-5: Common Basilisk Support Files ============================= The folder ``src/architecture/utilities`` contains a number of C code support libraries that simplify the mathematics of writing Basilisk modules. This page highlights some common libraries used. `astroConstants.h` :ref:`astroConstants` contains a range of orbital mechanics related variable definition. `avsEigenMRP.h` :ref:`avsEigenMRP` provides MRP capabilities to the `Intel Eigen library `__. `avsEigenSupport.h` :ref:`avsEigenSupport` provides a range of helper function to convert between C array variables and `Intel Eigen library `__ vectors and matrices. `discretize.h` :ref:`discretize` provides functions to discretize a real number. `gauss_markov.h` :ref:`gauss_markov` provides functions to apply a second-order bounded Gauss-Markov random walk on top of an upper level process. `geodeticConversion.h` :ref:`geodeticConversion` provides a collection of functions to convert to and from planet centered frames. `keplerianOrbit.h` :ref:`keplerianOrbit` class represents an elliptical orbit and provides a coherent set of common outputs such as position and velocity, orbital period, semi-parameter, etc. It uses the utility orbitalMotion to do orbital element to position and velocity conversion. `linearAlgebra.h` :ref:`linearAlgebra` provides a collection of functions perfrom 2D, 3D, 4D and N-dimensional matrix math in C `macroDefinitions.h` :ref:`macroDefinitions` provides a collection of convenient macro definitions `orbitalMotion.h` :ref:`orbitalMotion` provides a collection of orbital mechanics related function. `rigidBodyKinematics.h` :ref:`rigidBodyKinematics` provides a collection of rigid body kinematics transformations. This includes functions to map between a range of attitude coordinates. `saturate.h` :ref:`saturate` is used to saturate an output variable `signalCondition.h` :ref:`signalCondition` provides provides a low-pass filter to an output variable `simDefinitions.h` :ref:`simDefinitions` provides common simulation related definition such as default epoch states, etc.