|HP 20b: and ANS (or CHS and LASTx)|
Message #1 Posted by Karl Schneider on 26 Dec 2008, 7:13 p.m.
Hi, Thomas --
(NOTE: Again, some strange glitch in HTML, MoHPC Forum software, or my web browser prevents me from responding directly.)
Thanks for bringing this up. I haven't experimented much with the HP-20b since receving one, nor have I perused the Learning Modules.
It seems that "ANS" serves as "LASTx" in RPN mode. Indeed, the crux of the error is that the "+/-" operation replaces what had been available before, unlike traditional "LASTx", which did not replace the L-register, because another "+/-" or "CHS" could undo it.
Since I don't see "x< >y" or "SWAP" on the HP-20b (I'm sure it's hidden somewhere), I'll exploit commutativity of addition:
3.4567 [shift][sqrt][shift][ANS][shift][1/x][shift][ANS][shift][LN] 2[*][-][+/-][+]
This uses the same number of keystrokes.
3.4567 [ENTER][ENTER][sqrt][x<>y][LN] 2 [*][+][x<>y][1/x][-]
(This omits any necessary shift keys.)
Edited: 26 Dec 2008, 7:21 p.m.