The uses of hand-held PDA are so many, depending upon who has them – a Corporate executive, a Scientist, Teacher or Multi-media journalist and so on.  As such there are innumerable software solutions made available for varied PDA users with Palm Operating System interface.
For the use of mathematical calculations, which are too complicated for ordinary persons to make and comprehend, here is PDAcalc Classic (Palm OS) 1.67 software made available in the market.  This is a Palm OS based software which can be useful for utilities; calculations; Engineering education and Mathematical education.
PDAcalc Classic (Palm OS) is a general purpose programmable graphing calculator. Any one can make use of this software solution where no programming is needed for the basic calculations, including plotting functions, solving equations for unknown variables etc.  Without any programming experience you can write your own scripts. What is more, by following the simple examples published in the users manual (which is easy to read) you can start writing your own programs within no time.
There is a long list of features designed in this software and to quote a few –
3D graphics; Linear regression; financial functions; statistical functions; root finding functions; Fourier transforms (FFT); debug screen is color coded; graphs can be auto-scaled; equation solver worksheet; equations for variables can be solved; keyboard can be re-configured fully; complex numbers and functions; enable 3D functions such as drawing lines, rotate objects in 3D space etc.; calculus functions, integral, derivates etc.; plot functions can be used without programming; and user scripts are made available in the manufacturers’ website which can be loaded and run directly from their website.