Calculation of pi on many machines

[Werner]

My current HP-41 compatible version runs in less than a minute (58s) on the DM-42 on USB, producing 1017 correct digits, using
Pi = 16*ATAN(1/5) - 4*ATAN(1/239)
It runs unchanged on a 41, 42 and Free42/DM42, but will use all available precision, ie. 10 digits on a 41, 12 on a 42 and 34 on Free42/DM42.
It is written so that it can use any ATAN formula X*ATAN(N/D), as long as N^2+D^2 is less than 'half-length', ie 10^5 for a 41, 10^6 for a 42S and 10^17 for Free42/DM42.
Using another ATAN formula, I can get the DM42 USB time under 38 seconds (but it won't run on a 41 or 42 any more).

Cheers, Werner