Hi yakas, some great tips from Pilou above, and also if you want to make a curve by a math formula you might try Max's FxGraph plug-in from here: http://moi3d.com/forum/index.php?webtag=MOI&msg=6447.1

http://moi.maxsm.net/files/

There are instructions for how to install a plug-in here:
http://moi3d.com/faq#Q:_How_do_I_install_a_plug-in_script.3F

- Michael