Have you *used* any graphing calculator apps? I've found some that are 0.99 and then some that are $25, so I just want to hear some input before I buy one.
I use Graphing calculator, it was free when got it. It's good. I don't know how to do most thngs like finding the intercepts and such, but the interface supports the multitouch.
It does thing a bit differently compared to other available math apps: it understands math formulas of any complexity (multiple expressions with multiple variables) and provides a way to create sliders to control parameter values and interact with the formula graph. You can also email your formulas with graph previews, or export the graphs to the Photo album with the formula embedded in an inset. We will add new features based on customer requests.