QPlot

QPlot is an Advanced Matematical Calculator for Qtopia, featuring a nice calculation mode (you see the statement and the result), arbitrary precision calculations, an extensive math library (trig, inverse trig, hyp, inverse hyp, algebraic, etc.), integration, differentiation, quadratic differentiation, graphing (including the ability to easily move around and zoom in/out), equation solving (quadratically or using Newton’s method),an ability to write programs (and run them directly from desktop), and extensibility. (Source: http://freecode.com/)