  In this work we present a simple code to calculate tightly focused vectorial
light fields (propagating and evanescent) generated by input fields that have
arbitrary amplitude, phase and polarization. The program considers results from
previous studies, like integration via fast Fourier transforms to speed up the
integration. The calculations are done in a Cartesian coordinate system that is
convenient to compare with experimental results for beams that are shaped with
programmable optical elements like spatial light modulators or digital
micromirror arrays. We also discuss how to avoid diverging terms at the origin
by shifting the angular mesh by half a point and correcting the output by
cancelling the phase term that arises from the shifted Fourier transform.
