pgfplots - A TeX package to draw normal and/or logarithmic plots directly in TeX in two and three dimensions with a user-friendly interface and pgfplotstable - a TeX package to round and format numerical tables. Examples in manuals and/or on web site.
The title says it all. This was first reported at https://tex.stackexchange.com/questions/641917/using-pgfplotspointgetcoordinates-together-with-fillbetween-command.