This equation is not very precise, but an approximation of actual displacement.
I don’t know how do implement it in Matlab (would probably be the easiest way), but if you have already exported it to CSV, you can load it into a GIS (e.g. QGIS) together with a raster of the local incidence angle (exported from SNAP) and extract the angles to each PS point. In the attribute table of the points you could then apply the equation based on both variables.
I explained how to load the CSV into QGIS here: StaMPS-Visualizer, SNAP-StaMPS Workflow - #315 by ABraun