() precedence

12082022, 10:23 PM
Post: #21




RE: () precedence
Right.


12092022, 12:15 AM
Post: #22




RE: () precedence  
12092022, 02:52 PM
Post: #23




RE: () precedence
I don't think that anyone has mentioned that the Prime has *both* operators. A subtraction operator and the unary minus, each with different symbols. In this case, I think the unary minus should bind tighter to the number.


12092022, 04:02 PM
Post: #24




RE: () precedence
(12082022 09:21 PM)Thomas Okken Wrote: Unary minus should have the same precedence as binary minus, that's the way it works in standard mathematical notation. Another way of understanding it is that x is shorthand for 0x. This is how modern Fortran does it, but many others had unary +/ above * / mod. (a)*b = (a*b) (a)/b = (a/b) We don't notice any difference until we added MOD operator. For example, this is from HP Prime emulator: CAS> 2 * 3 MOD 4 → 2 CAS> 2 MOD 3 * 4 → 8 This showed MOD had same precedence as MUL. It just evaluate from left to right. CAS>  10 MOD 7 → 4 CAS> 0  10 MOD 7 → 3 This showed UNARY MINUS had higher precedence than MOD, thus also MUL and DIV 

12102022, 01:51 AM
Post: #25




RE: () precedence
(12092022 02:52 PM)KeithB Wrote: I don't think that anyone has mentioned that the Prime has *both* operators. A subtraction operator and the unary minus, each with different symbols. In this case, I think the unary minus should bind tighter to the number. I never noticed the Prime display of negative versus negation, but you are correct. Neat! The Prime negative indicator reminds me of the APL "high minus" in which a negative number uses the "¯" symbol to indicate a negative number, as in ¯2 as opposed to 2 That of course means ¯2 is negative two (not the negation of two or 02) and ¯2*2 (* is power of) equals 4 as expected, whereas 2*2 is ¯4 because APL expressions are evaluated right to left (no function precedence nonsense), and thus negation is applied last. The '' symbol is subtraction with a LHS argument and negation without, so then 22 is 4 (obviously ) APL is a mathematical notation developed by a Mathematician. Wish I had an APL calculator Remember kids, "In a democracy, you get the government you deserve." 

12102022, 03:42 AM
Post: #26




RE: () precedence
(12102022 01:51 AM)mfleming Wrote: APL is a mathematical notation developed by a Mathematician. Wish I had an APL calculator Now that is a calculator keyboard I would really like to see!! Bob Prosperi 

12102022, 04:18 PM
(This post was last modified: 12102022 04:18 PM by Maximilian Hohmann.)
Post: #27




RE: () precedence
Hello!
(12102022 03:42 AM)rprosperi Wrote: Now that is a calculator keyboard I would really like to see!! If you have a device that runs Android you can compile an APL calculator app from here: https://github.com/dzaima/APL/tree/master/AndroidIDE There are some pictures of the keyboard furher down the page. To be honest, for me a keyboard like that looks rather scary ;) But at least one never needs to think about operator precence ever again. Regards Max 

12102022, 04:38 PM
Post: #28




RE: () precedence
(12102022 04:18 PM)Maximilian Hohmann Wrote: But at least one never needs to think about operator precedence ever again. Well, one doesn't need to think about operator precedence if one uses RPN... OTOH, it should be possible to make an APL interpreter for the Prime although it would require the use of custom characters since the Prime doesn't include the APL code page. 

12102022, 05:57 PM
Post: #29




RE: () precedence
(12102022 04:18 PM)Maximilian Hohmann Wrote: But at least one never needs to think about operator presence ever again. One never has to worry about automatic precedence ever again but you still have to worry about precedence. Only now, it's all up to you! Tom L Cui bono? 

12102022, 06:56 PM
Post: #30




RE: () precedence
(12102022 04:18 PM)Maximilian Hohmann Wrote: Hello! Thanks Max. Those keyboard images confirm my very worst fears of how truly hostile such an APL keyboard would appear. Note I said "...would really like to see...". I certainly would never want to use such a beast, I fear it may cause permanent loss of brain function as regards using RPN. Waaaay too risky... Bob Prosperi 

12102022, 10:22 PM
Post: #31




RE: () precedence
I have mixed feelings about APL it exemplifies the ideal of a small, flexible set of powerful tools, which I admire. There may well be sound ideas behind the symbols but they are nonintuitive and hermetic. Overall a mixture of the good, the notsogood and the just plain crazy!
There is a newer dialect called J which uses standard ASCII characters but it manages to be even less readable. 

12102022, 11:23 PM
Post: #32




RE: () precedence
(12102022 04:18 PM)Maximilian Hohmann Wrote: Hello!I tried that a few years ago but found it was difficult to view on the small screen of a phone. Looks like they've added connectivity to a Dyalog server via Ride, so I'll have to try this again on a tablet. Thanks Max. (12102022 06:56 PM)rprosperi Wrote: Thanks Max. Those keyboard images confirm my very worst fears of how truly hostile such an APL keyboard would appear. Note I said "...would really like to see...". I certainly would never want to use such a beast, I fear it may cause permanent loss of brain function as regards using RPN. Waaaay too risky... Actually, an APL calculator would look an awful lot like a DM42 with a slightly different faceplate. If you're doing some quick calculations you wouldn't want to type 1○○0.25 to get the sine of pi/4 or ⍟27 for natural log of 27. Just leave the main keys as they are. All those chickenscratch symbols would be available from a few soft menus above the unlabeled top keys, much like the DM42 or WP43. Have an option to show your equation asis or display the APL equivalent to what you typed in. Learn APL as you go along. The display would look like a series of expressions and results displayed like the Prime or HP48/50. Now how might one combine APL with an RPN stack Remember kids, "In a democracy, you get the government you deserve." 

12112022, 08:29 AM
Post: #33




RE: () precedence
On the slightly drifted topic of APL in the wild, the luggable MCM/70 from 1974 (announced in '73) is well worth knowing about:
https://museum.eecs.yorku.ca/exhibits/sh...exhibit_p1 

12112022, 10:38 AM
Post: #34




RE: () precedence
Hello!
(12112022 08:29 AM)EdS2 Wrote: On the slightly drifted topic of APL in the wild, the luggable MCM/70 from 1974 (announced in '73) is well worth knowing about Very interesting calculator, thanks for posting the link. The keyboard seems to be of the the "mild APL" variant though. Just a few mathematical symbols on shifted keys most of which even I recognise :) Regards Max 

12112022, 01:27 PM
Post: #35




RE: () precedence
(12112022 08:29 AM)EdS2 Wrote: On the slightly drifted topic of APL in the wild, the luggable MCM/70 from 1974 (announced in '73) is well worth knowing about: Pretty amazing given the limited capability of the 8008. I can remember the early portables (uh, luggables) with builtin cassette drives. Here's something from '75 I occasionally search The Bay for https://en.m.wikipedia.org/wiki/IBM_5100 APL the language (as opposed to the notation) would never have come about were it not for the interchangeable type balls of the IBM Selectric typewriter. Remember kids, "In a democracy, you get the government you deserve." 

12122022, 04:37 PM
Post: #36




RE: () precedence
(12102022 01:51 AM)mfleming Wrote:(12092022 02:52 PM)KeithB Wrote: I don't think that anyone has mentioned that the Prime has *both* operators. A subtraction operator and the unary minus, each with different symbols. In this case, I think the unary minus should bind tighter to the number. This is probably not the APL calculator you could dream of, but it may be of interest to you and/or other readers. https://home.gwu.edu/~nbrenner/ ↳ direct link: https://home.gwu.edu/~nbrenner/49GNotes.txt BTW: on RPL calculators (28 → 50), the algebraic expression '2^2' gives 4 as a résult. Bruno Sanyo CZ0124 ⋅ TI57 ⋅ HP15C ⋅ Canon X07 + XP140 Monitor Card ⋅ HP41CX ⋅ HP28S ⋅ HP50G ⋅ HP50G 

12122022, 10:13 PM
Post: #37




RE: () precedence
Nice find! I'll have to spend some time with this and my 50...
Remember kids, "In a democracy, you get the government you deserve." 

12122022, 11:56 PM
Post: #38




RE: () precedence
(12122022 04:37 PM)FLISZT Wrote: (…)  A small addition to my post  Take a look at: https://www.hpcalc.org/details/7412 Bruno Sanyo CZ0124 ⋅ TI57 ⋅ HP15C ⋅ Canon X07 + XP140 Monitor Card ⋅ HP41CX ⋅ HP28S ⋅ HP50G ⋅ HP50G 

12132022, 03:59 PM
Post: #39




RE: () precedence
The problem here is that we're using the same "" character for three different, albeit related, concepts:
If only we used a different symbol to signify that a number is negative, all this confusion would disappear. Unfortunately, we're stuck with the notation that we have. 

12132022, 06:12 PM
Post: #40




RE: () precedence
(12132022 03:59 PM)David Hayden Wrote: we have an understandable aversion to saying that to square the number 2.3, you must put parentheses around it (2.3)^{2}) That "we" does not include just about every single math textbook I have ever laid eyes on. See my example in the second post of this thread for a very typical example... 

« Next Oldest  Next Newest »

User(s) browsing this thread: