# Lenstool Manual¶

## Description of the Parameter file¶

You can find a description of the parameter file description here.

The parameter file must end with the .par extension.

## Description of the input and output files¶

Lenstool may need several data files as input, and may produce several files as output. You can find a description of their format here.

## Post-processing tools¶

Beside the lenstool executables, a list of post-processing tools located in the ./utils and ./perl directories can be used to post-process the output of an optimization. In short, they allow the user to propagate the errors on the model's parameters into other observables.

They are described here.

## Description of the $\chi^2$ calculations¶

The $\chi^2$ is computed for the different datasets (SL, WL, etc) in the o_chi.c file. The details about these calculations are given here.

## List of supported analytic potentials¶

Lenstool can model many different lensing analytic potentials. You can find the complete list here.