FERRE is a data analysis code written in FORTRAN90. It matches models to data, taking a set of observations and identifying the model parameters that best reproduce the data, in a chi- squared sense. Model predictions are to be given as an array whose values are a function of the model parameters, i.e. numerically. FERRE holds this array in memory, or in a direct-access binary file, and interpolates in it. The code returns, in addition to the optimal set of parameters, their error covariance, and the corresponding model prediction.
The FERRE fortran code was written by Carlos Allende Prieto. David Nidever repackaged it, added some Python code to call the Fortran program and added it to Pypi so it can be pip installed.