Calculator based user interface
Graphulator is a graphing calculator application for Apple's iPhone. Graphulator allows the user to enter a mathematical formula using a familiar calculator-style interface, then display a two dimensional graph of that formula.

Graph of the sin(x) function
The user uses a swipe gesture to move the graph around, or a pinch gesture to zoom the view of the graph. Optional settings allow the user to display a grid on the graph, and to lock the scale of the x and y axis to be the same.

You can read more about Graphulator’s features and you can see more screenshots.

Graphulator can be purchased through the iTunes App Store (link opens in iTunes).