Of the ones I have looked at, Origin by Microcal (Northampton MA) seems most likely to be a candidate. I tried a few thousand points and it handled them well, but I never tried > 100K. By contrast Jandel SigmaPlot is a very slow performer with arrays >10 points. It just does too many repaints and does them too slowly. James W. Cooper Manager of Programming and Scientific Solutions We're not opening old Windows, we're opening new doors: to Fibber McGee's Closet!