Deep Pi on the HP-41cx


I was not able to run the Deep Pi program after keying in the program steps as listed on

Should X<>0? (a nonexistent function) actually be X<> 00 (X swap with register 00 ?)

The program lines are not numbered but this step occurs, by my count, at lines 321, 338, and 408, of 511.

The flying goose justs runs forever when I execute the program.

Are there perhaps some typos in the program listing?

Any help would be greatly appreciated.

Thanks, Mark Taylor


The code looks correct. Are you sure you are let it run long enough for an answer? I ran the code in V41 with turbo on and it took a minutes or two to run. Try starting it off on say the first set of numbers and let it run for about 5 minutes and see if it finishes.


X<>0? does exist on the 41cx (using the not-equals sign which you key in with <shift>H).


Thanks Richard and Garth!

It took my 41CX over 30 minutes to generate the first set of 6 digits. The fourth set of 6 digits took over 2 hours to generate!

Comments anyone?


hi mark,

sorry if this was confusing, but X<>0? is not a memory exchange but a compare against zero.

good luck,


Thanks Hugh!

Please see my earlier post. My 41CX has been running set after set of 6 digits all weekend. Currently calculating digits 55 to 60. Each set has been taking 2 hours or so to generate. Should it take that long?

Thanks again,
Mark Taylor


I'd get a new cookery book as my 'pies' (note the spelling) take about 1 hour to do. As far as depth goes about 6 inches (150mm) is good, any deeper and the filling doesn't cook properly (for a 12 inch / 300mm pie dish).

Whats this HP-41cx thing? A new kind of programmable microwave or food mixer 'my boys' at HP have been developing?

To think some people think I don't know anything outside of company financing.

P.S. If you are making goose pie, best not let it run forever round the kitchen - it makes a horrible mess.

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