Longest computation that your calculator performed for you?

[Garth Wilson]

30+ years ago I needed to figure out the ringing time constant of a circuit with inductors, capacitors, and resistors, and didn't have the math background to do it the fast way, so I wrote a program for my TI-59 to do it kind of like a Simpson's approximation of an integral, chopping the ringing waveform up into tiny slivers and simulating the behavior of each of the components as they worked together. It ran all night—or maybe 24 hours. I think I did it a few times with different step sizes to make sure I had really converged on a valid answer. I'm not nearly as strong in math as some on this forum are, but I can always find a way to brute-force something to get the answers I need.

A few years ago I used my HP-71, in BASIC, to generate large look-up tables (most being 65,536 cells each, and 16-bit, meaning 128KB per table) for hyperfast, accurate, 16-bit scaled-integer math, to use as a virtual co-processor for hardware that didn't have a normal co-processor. It took my HP-71 a few weeks to generate the tables and convert to Intel Hex files. I posted them, along with a discussion of the value of scaled-integer math and how to use it effectively, and information on how each table was calculated, on my website, at http://wilsonminesco.com/16bitMathTables/ .