(RPL) percentage function % not preserving stack level 2
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01-05-2019, 02:12 AM
Post: #5
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RE: (RPL) percentage function % not preserving stack level 2
thanks very much all, that's most helpful.
(01-05-2019 12:53 AM)Joe Horn Wrote: IMHO, Y was preserved in the 4-level RPN machines (after performing the % function) due to the very limited size of the stack. Since RPL machines have no such limitation, and since LASTARG returns both X and Y, there is no need for the function to preserve Y on the stack; the user is free to make as many copies as needed of any stack levels. I'd forgotten that LASTARG returns multiple args, that's useful, thanks. The minor irritation with your RPL example above is that both DUP and % are hidden in different menus, so not as easy to type, e.g. it would be: RPL: X TOOL-STACK-DUP Y MATH-REAL-% which is a lot more button presses. I could use ALPHA-LS-1 for %, of course, but that's no less presses. Ah! But I can use Enter twice for DUP, OK, that's good (01-05-2019 01:13 AM)Albert Chan Wrote: My guess is RPL tried to keep a consistent interface, returning 1 item for each operation. It's ironic, in some ways, since RPL systems don't need to worry about consuming stack. (01-05-2019 01:30 AM)rprosperi Wrote: As others have noted, RPL tends to be more 'stack pure' while RPN did a lot of 'convenient', though non-standard, things which IMHO really did make them more useful. Returning dual results for % is the exact example I cite most when discussing this. Yes, I like %T too. OVER SWAP: excellent! thank you again, thanks to all. Cambridge, UK 41CL/DM41X 12/15C/16C DM15/16 17B/II/II+ 28S 42S/DM42 32SII 48GX 50g 35s WP34S PrimeG2 WP43S/pilot Casio, Rockwell 18R |
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