TouchPlot

TouchPlot is a powerful grapher with a long list of features:

• formula editor with custom keyboards along with prettyprint display of the formula being entered. Note that the syntax being used to enter a formula is based on direct polish notation. There is a learning curve, but usually it becomes really slick with practice. Please visit the website for more details about that, see in particular the tutorial section.
• symbolic differentiation
• representative curves of functions with a focus on accuracy and speed
• calculation of first terms of iterative sequences, and graphical representations of them
• parametric curves in cartesian and polar coordinates
• solutions of equations and inequations, drawing of surfaces with equation z=F(x,y)
• solutions of ordinary differential equations (first and second order) with vector fields
• some user defined constants with sliders to observe how a curve is changed by a parameter, or to adjust initial conditions of a differential equation particular solution...
• logarithmic scales if needed, adjustable separately for horizontal and vertical axis.