easi is a library for the Easy Initialization of models
in three (or less or more) dimensional domains.
The purpose of easi is to evaluate functions $f : R^m \rightarrow R^n$,
which are described in a YAML configuration file.
In grid-based simulation software, such as SeisSol,
easi may be used to define models.
In SeisSol, the function $f$ maps every point in space
(say $x,y,z$) to a vector of parameters (e.g. $\rho$, $\mu$, and $\lambda$),
which define a rheological model.
Here, over 5000 lines of model-specific Fortran
code could be replaced with YAML files.
The reference documentation can be found on
Read the Docs
or be downloaded as a PDF manual.