|Re: HP 15c searchable Adv Fun Handbook (link) - done by Joe Horn|
Message #4 Posted by Valentin Albillo on 19 Nov 2011, 3:54 p.m.,
in response to message #1 by gene wright
Thanks for the link, Gene, it's a very nice scan and much appreciated.
Actually, I really love those old HP manuals and Owner's Handbooks of the golden age, and this particular one is really among the very best and most interesting of them all and really lives up to its title, being full to the brim with quality advanced info and examples.
However, all isn't perfect and there's the odd suboptimal programming in there as well, which is particularly rare in such a state-of-the-art handbook. One such instance is the routine found in page 119 for "Constructing an Identity Matrix", which ineffciently needs 12 steps and 3 registers to do the task and it's quite slow to boot.
Actually, I asked for such a routine in one of my very first HP-15C mini-challenges posted to this forum many years ago, with my own solution being:
STO MATRIX A
"u" STO A
which is just 10 steps long (including LBL and RTN), and only takes a maximum of 3 seconds for a 7x7 matrix, which is the largest possible size the HP-15C's memory allows. You can substitute MATRIX A and STO A for whatever desired matrix, A to E.
Best regards from V.