New Datafile articles


Hi all,

Just a quick post (too busy am I ...) to let you know
that two new articles from mine do appear published in
the latest May-June issue of Datafile (V24 N3), namely:

  • HP-71B Fantastic FOUR

    This completes my survey of the awesome HP-71B Math ROM's capabilities featured in my previous HP-71B Math ROM Baker's Dozen (Vols. 1 & 2) articles (Datafile V24N1 & V24N2), with a 14th item, this time entirely dedicated to an amazing and, to most people, unexpected application of the rarely used FOUR keyword. The 8-page article includes an extremely short (8-10 line) subprogram to prove the point, which implements the desired functionality by using FOUR at THREE different places ! :-)

    ... And in case you might be wondering what it does do in 8 lines, well, just things like this:






    only real fast and with much bigger numbers ...

  • HP-71B Sudoku Solver's Sublime Sequel

    A sequel to my original 35-line HP-71B Short & Sweet Sudoku Solver published in Datafile V24N2, which improves its speed enormously at the expense of just 10 additional lines of code, for a total of 45 lines (half a regular 80-line printed page), well under 2 Kb. Together they form a combined 19-page article which discusses important techniques for this kind of solvers (e.g., bitboards and boolean operations), plus it includes a thorough, 15-item Test Suite, to allow the reader to test any Sudoku solvers out there, or even his/her own human capabilities.

    (Matter of fact, I did have this 'sequel' ready and working perfectly before my originally submitted article was published, and I contacted Datafile's Editor, Bruce Horrocks for him to drop it and publish this improved version instead, which would thus have appeared in V24N2. Bruce agreed, but personal complications arised and I was unable to find enough free time to rewrite the already existing article from scratch, so I further told him to go on with publishing the first version anyway, till I could find the time to submit the improved version properly formatted for its publication in Datafile. This is it!)

I hope you'll enjoy them. Also, in this same issue, "Slow Sudoku on the HP-12C" by Tony Hutchings boldly goes where no one dared before, implementing a Sudoku solver/assistant in both a regular HP-12C as well as a 200-step version for the HP-12C Platinum. For such a fan of the HP-12C as myself, this is really a must reading as well.

Best regards from V.

Edited: 20 June 2005, 5:51 a.m.


FYI, Tony's surname is spelled without a 'g'.


Hi Valentin,

I didn't know this (not so new) method to multiply two long integers using FFT. Your articles are always the opportunity for me to improve my mathematical knowledge...

Maybe it's not the most efficient method on the HP-71B due to the very slow trig function calculation, but it can be done!



Hi, Jean-François !

J-F posted:

"Your articles are always the opportunity for
me to improve my mathematical knowledge..."

Thanks for your appreciation of my articles. As I've said
a number of times before, were it not for your *wonderful*, free emulator for the HP-71B,
Emu71 and your kindness in providing materials and answering my questions, many of them would not even exist. So you should certainly share any merit they might have.

"Maybe it's not the most efficient method on the HP-71B due to the very slow trig function calculation, but it can be done!"

And in 10 lines or less !! :-) As for speed, I think FOUR is quite fast indeed, see the times quoted by HP for it in the last pages of the Math ROM's Owner's Handbook.

Thanks again and best regards from V.

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