HP71 Scale10() function

[Valentin Albillo]

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Hi, KeithB,

(09-12-2022 06:55 PM)KeithB Wrote:  The hyperbolic thread made me drag out my HP71 Math Pac manual and I saw an entry for the Scale10() function. What good is it? Has anyone used it? Was it ever used on any other calculators?
I note that they did not even bother to put in an example for it!

It's a mostly useless function, IMHO. I guess they put it as a keyword because it already was in the ROM as an internal routine, so making it user-accessible was just a matter of providing a keyword for it and simply calling the internal routine, as in the case of the REV$ string function, which was absent from the mainframe's instruction set but implementing it in a LEX file required just assigning a keyword to it and directly calling the internal routine already present in the System ROMs without further ado. Perhaps the implementation of IEEE math did require having the SCALE10 function exposed to the user for full compliance.

I only used it a very few times (perhaps twice or thrice) and mostly to check its suitability for very specific one-of-a-kind purposes, but as the usual suspects at HP decided to burden it with so long a keyword (7 characters !), it was problematic to include several instances within a single math expression, where it would be most useful, without overflowing the length of the line. They did the same with the Math ROM's INTEGRAL keyword, which J-F Garnier shortened in his new revamped Math ROM.

Also, it seems that accessing a function in the Math ROM does carry some overhead in execution time, so I found it slower than its obvious equivalent ( SCALE10(X,N) -> X*10^N ), if I recall correctly, so in the end I considered it useless and even aesthetically unappealing in listings and discarded using it for good.

V.