Prime Factors

05182015, 06:10 PM
(This post was last modified: 05192015 01:13 PM by Dave Britten.)
Post: #1




Prime Factors
In an attempt to rival Doom for the largest number of systems to which it's been ported, here's the usual HP 67 "mod 30" prime factors program for the 41C/CV/CX.
Enter a positive integer, and XEQ FCTR. Press R/S to view each factor. Zero will be displayed when there are no more factors. Note this is a pretty straight port, and hasn't been fancied up with any 41specific capabilities (yet). EDIT: Here's a slightly improved version with a couple optimizations, and multiplicity display for factors (e.g. 3^2, 7^3, etc). Code: 01 LBL FCTR 

05182015, 08:31 PM
Post: #2




RE: Prime Factors
(05182015 06:10 PM)Dave Britten Wrote: Note this is a pretty straight port, and hasn't been fancied up with any 41specific capabilities (yet). You might have a look at a program for the HP42s which uses the same idea. Cheers Thomas 

05192015, 02:58 AM
Post: #3




RE: Prime Factors
(05182015 08:31 PM)Thomas Klemm Wrote:(05182015 06:10 PM)Dave Britten Wrote: Note this is a pretty straight port, and hasn't been fancied up with any 41specific capabilities (yet). Thanks Thomas. Clever use of tcopy there. I see a couple things that could be issues for a 41 port: the use of recall arithmetic, as mentioned in that thread, AIP, which requires the appropriate module or alternative code, and the alpha register being limited to 24 characters. I don't recall the 42S alpha limit, but I think I remember it being larger. I changed my version a bit to display multiplicity of factors as they're found (3^2, 5^3, etc.) and also replaced the / FRC bits with MOD, which appears to be about 20% faster. I'll probably post the updated code tomorrow. 

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