hmm i think der1 is the first derivative and nDer is the numericial Derivitive. I guess they are calculated differently. Garvin Cung wrote: > on the ti-85, wat is the difference between 'der1' and 'nDer' in the > "CALC" menu? > > thanks > > --garvin > _______________________________________________________ > Garvin Cung > E-mail: garvinc@iname.com > URL: http://www.geocities.com/ResearchTriangle/lab/2240