X-Cal app for iPhone and iPad

x-Cal is an ergonomic scientific calculator, in both portrait and landscape orientations, using RPN (Reverse Polish Notation)
Great for professional and educational use, it allows to quickly develop an understanding of register operations and basic programming
Features fixed, scientific or engineer number formats, trigonometric and hyperbolic calculations in radians, degrees or grades, basic statistical computations, linear correlations, combinations, etc.
Swipe on the top result display area to view the arithmetic register stack, tap on the top to display other registers such as storage register, statistical registers and program steps
Record programs such as a quadratic equation solver, or display graphs to visualize functions y = f(x)
At any time look, copy and paste text style computations into e-Mails, notes, etc.