From Natty Software:
Natty Scientific Calculator is an original scientific calculator. Using an advance mathematical parser (JEP), it is able to calculate mathematical equations very accurately. What makes this calculator different is its simplicity. It is much easier to use than its competitors and any input can immediately be converted to a graph.
Natty Scientific Calculator features:
Scientific and engineering calculations.
Complex numbers can be inserted and stored (e.g. (radians&angle) OR (real+imaginary)).
Easy store and recall.
Definite Integration function (e.g. I(1,5,sin(x)+2))
Differentiation function (e.g. D(3,cos(x^2)))
y(x) graphing function.
polar graphing function.
parametric graphing function.