Hi qibentie, is there any particular function curve that you're interested in?

Probably making a full blown math graphing calculator built directly into MoI would be out of the scope of what I could do, but it is possible to do a plugin to make a particular function curve. The sine wave curve generator here is an example of that:
http://moi3d.com/forum/display.php?webtag=MOI&msg=1519.38

Also if it is possible to export sampled points from a function curve in GeoGebra to a text file with 1 point on every line of the file, that can then be imported into MoI using the import points plug-in that Petr wrote here:
http://kyticka.webzdarma.cz/3d/moi/#ImportPointFile

- Michael