HP Forum Archive 18

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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. Traditional RPN: 3.4567 [ENTER][ENTER][sqrt][x<>y][LN] 2 [*][+][x<>y][1/x][-] (This omits any necessary shift keys.) -- KS Edited: 26 Dec 2008, 7:21 p.m.

Re: HP 20b: and ANS (or CHS and LASTx) Message #2 Posted by Thomas Klemm on 26 Dec 2008, 8:11 p.m., in response to message #1 by Karl Schneider Quote: I'm sure it's hidden somewhere )x Quote: 3.4567 [shift][sqrt][shift][ANS][shift][1/x][shift][ANS][shift][LN] 2[*][-][+/-][+] This can still be improved by one keystroke: 3.4567 [shift][sqrt] [shift][ANS] [shift][1/x] 2 [shift][ANS] [shift][LN] [*] [-] [-]

Re: HP 20b: and ANS (or CHS and LASTx) Message #3 Posted by Karl Schneider on 27 Dec 2008, 2:08 a.m., in response to message #2 by Thomas Klemm Ah! Those cris-crossing arrows represent the "exchange/swap" operation; I thought it was a pair of scissors for cut-and-paste. Actually, it's clever to use a pair of keys for double-duty: parentheses for algebraic; roll_down and exchange for RPN. So, I guess "ANS" retains the result of the previous calculation, explaining why "+/-" changes the result of ANS, but entering new data ("2" in your example) does not -- at least, until another operation is completed. ANS is therefore not a direct replacement for LASTx. The "Traditional RPN" method also takes 13 keystrokes on the HP-20b after entering the value of x: 3.4567 ENTER ENTER shift sqrt )x shift LN 2 * + )x 1/x - -- KS Edited: 27 Dec 2008, 3:09 a.m.

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