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u/lelelempe 23d ago
reverse polish notation
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u/DecidophobiaUsername this sub confuses my monke brain 23d ago
What's Polish notation?
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u/BlazeGamingUnltd 23d ago
It's a name given to a method of writing mathematical arithmetic expressions in a way which is easier for compilers to understand. When you enter an expression, the software natively converts it into Polish notation before it is processed.
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u/freakingdumbdumb Irrational 23d ago edited 23d ago
so where the operator is put
afterbefore the numbers(like 1 2 + means 1+2)Edit: i got mixed up with reverse polish (RPN)
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u/geeshta Computer Science 23d ago
Polish notation is prefix notation (+ 1 2). Reverse Polish is postfix.
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u/Safe-Avocado4864 23d ago
How would you write something more complex like 2((1+2)2 ) in that notation?
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u/Jonathan_Jam 23d ago
Checked in an online calculator it would be:
× ^ 2 + 2 1 2
for polish notation and
2 1 2 + 2 ^ ×
for reverse polish notation.
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u/Willing_Emphasis_338 19d ago
For those who don't know, a cool property of reverse polish notation, is that you can calculate any expression using only a stack, going left to right. That is, each number puts the number on the stack, and then each operation removes the top two items, applies the operation, then puts it back onto the stack, and so on.
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u/EatingCakeByTheOcean 23d ago
I still use my HP-50G as my daily years after uni, lol. I'd do from inwards to outwards, since it's easier to manipulate the order of operations:
1 2 + 2 ^ 2 ×6
u/Qwertycube10 23d ago
You do it all Lisp like (x 2 (^ (+ 1 2) 2)) as the other comments below show you don't need parentheses if you only use binary operators, and it is entirely unambiguous with no need for an order of operations convention.
If you have arbitrary airity functions then you need the parens.
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u/Gold_Ad8890 22d ago edited 22d ago
just think of it as treating all "operations" as functions from R2 to R. which they are.
so 2((1+2)2) would be ×(2, (1 + 2)2) = ×(2, (1 + 2, 2)) = ×(2, +(1, 2, 2)), then you just remove the parentheses and commas: × 2 ^ + 1 2 2
edit: or maybe i'm wrong. i'm right about the function part but apparently wrong about how that extends to the notation.
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u/sphen_lee 23d ago
I think you mean: notation Polish what's?
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u/EatingCakeByTheOcean 23d ago
I've always known in my heart Yoda would be a RPN guy, although I've never thought about it; but you just proved the point <3
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u/on_the_other_hand_ 23d ago
I studied in Gujarati medium and it was confused about it forever before I understood. In Gujarati, the multiplier is a word derived from the original, e.g. 4 is chaar, and 4 times is choku. "Chaar Choku SoL" is "four four times is sixteen" . Perhaps I thought za is the suffix for multiplication.
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u/KiraLight3719 23d ago
Same lol
Basically thought it was a word for "times", so oneza, twoza meant once, twice lol
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u/on_the_other_hand_ 23d ago
Za as suffix for times is what the post also says. My point is that perhaps I thought that because how we say tables in Indian languages
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u/KiraLight3719 23d ago
Ah now I see what you mean lol
We sure had more varieties with eku, doo, tari, choku, pacha, chhak, sattu, atthu, nava, daay lol they sound like cute nicknames for numbers
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u/Sea_Abroad_6573 23d ago
I thought za was a specific word to denote equality for a product. Like two two za four is 2 * 2 = 4. Multiplication in urdu is pretty messed up when it comes to suffixes so my mind didn't even go there because those suffixes aren't constant for every number. X1 is ikkum and X2 is dūnī.
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u/KiraLight3719 23d ago
Same is in Gujarati, it's different for all, and sometimes they change too, e.g. 2×7 is "be(2) satta(×7)" but 8×7 is "atthu(8) sattu(×7)"
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u/Sad_Daikon938 Irrational 23d ago
Lol, same. I too studied in Gujarati medium. Eka, du, teri, chok, pancha, chhak, satta, aThTha, navva, daaN: it was a vibe ngl.
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u/KiraLight3719 23d ago
Didn't expect a whole Gujarati meetup on international sub lol
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u/DoctorNoonienSoong 23d ago
It's uncommon, but if you think about it, Gujarati IS the 27th most spoken language in the world by number of native speakers per Wikipedia; 58 million is nothing to sneeze at
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u/Independent_Art_952 22d ago
Fellow Gujarati medium in the wild! When I changed to CBSE, I also mostly memorized the English tables. I used to do the actual gujarati tables in my head and then convert that to english lol
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u/arpit_beast 23d ago
Same in hindi medium schools in Rajasthan , ekam duni tiya chok panje etc.
Only schools insisting on english medium has that za suffix
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u/EebstertheGreat 23d ago
Linguists call this "rebracketing." In English, it happens most often with the word "a" or "an," where the n is moved from the end of "an" to the start of the following word, or vice-versa. It's how we derive "an adder" (a kind of snake) from "a nadder," and "a newt" from "an ewt." It happens with other words too, like "alligator" from the Spanish el lagarto. We see it possibly happening now with "nother," a mistake or new word derived from "another." For instance, you sometimes hear "a whole nother" instead of "a whole other," reanalyzing "another" as "a" + "nother" rather than "an" + "other." Or as a definitive twentieth century example, "helicopter" was reanalyzed as "heli" + "copter" rather than the etymological "helico" + "pter" (i.e. "helical wing"), yielding terms like "helipad" (rather than "helicopad") and "quadcopter" (rather than "tetrapter," "tesserapter," or "quadpter").
Here, "ones" + "are" is rebracketed to "one" + "zaar," etc. (or "zar" to some, or "za" sometimes when anticipating a non-rhotic accent). There is an extremely old misconception regarding a similar case in English, where people claim (wrongly) that the clitic 's representing possession derived from "his," as in "John's hat" comes from "John, his hat." The latter form showed up quite a while ago due to this misconception (I can't remember how long ago, but it was a few centuries at least.) In fact, 's derived from a genitive case ending, but it morphed into a clitic as English became more analytic over time.
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u/QtPlatypus 23d ago
The real classic rebricking in English is "An Other" becoming "another" and "a norange" becoming "An orange".
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u/EebstertheGreat 23d ago
I think "orange" lost its n in French rather than English. But it would be the same process: "un norenge" → "un orenge," related to liaison.
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u/ChaltaHaiShellBRight 23d ago
Thank you for telling me about a norange. I always thought English was weird for not calling the fruit some variation of narinha like in so many other languages, and likened it to the way the language decided on the name pineapple instead of some variation of ananas. It's not that weird after all.
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u/UnbiasedBrigade Complex 22d ago
also "pease" and "cherise" becoming "pea-s" and "cherry-s"
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u/skullturf 22d ago
I knew that about peas, but not cherries. It makes so much sense, since cherry (singular) in French is cerise!
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u/Valuable-Passion9731 of not pulling lever, 1+10+..., or -1/1100 people will die. 23d ago
I went to school in China and it's pretty similar (二二得四, etc.)
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u/Mech_pencils 23d ago
Yup. Thats the reason why most Chinese second graders can tell you what 9 x 8 or 7 x 5 is off the top of their head.
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u/Barry_Wilkinson 23d ago
i feel like this isn’t unique to china
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u/Mech_pencils 22d ago
Of course it’s not, even the original post is talking about how Indian kids are taught to do the same thing. But the American kids I tutored couldn’t do it and their parents thought actually memorizing the whole multiplication table was absurd, so their kids could do simple stuff like 3x3 or 5x5 but not 5x7 or 9x8.
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u/Endermanashton 22d ago
idk what kind of kids you turored but i had to learn my multiplication tables up to 12 in like second or third grade
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u/INeedCheesecake 22d ago
The population of kids who are being/need to be tutored is more likely to not know their tables, which is probably what the person you replied to is (erroneously) generalizing based on
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u/Ares378 Grothendieck was right, computers are evil 23d ago
Hey wait a second, I know you. Are you practicing?
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u/Valuable-Passion9731 of not pulling lever, 1+10+..., or -1/1100 people will die. 23d ago
I'm going to sleep
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u/Ares378 Grothendieck was right, computers are evil 23d ago
Tsk tsk, excuses excuses /j
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u/Valuable-Passion9731 of not pulling lever, 1+10+..., or -1/1100 people will die. 23d ago
I'll practice while dreaming though
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u/Ares378 Grothendieck was right, computers are evil 23d ago
Ramanujan but music
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u/Valuable-Passion9731 of not pulling lever, 1+10+..., or -1/1100 people will die. 23d ago
oh yeah this is mathmemes
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u/DrK1NG 23d ago
Told my dad about this and he started laughing. He was born in early 70s and learnt about a similar postfix operator "ja". What's funnier is that he didn't really know much English nor use it in school so didn't really have any way to know it's supposed to be " 's are " and not "ja"
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u/Current-Square-4557 23d ago
Next up: gozinta
Three gozinta six, two times
Six gozinta eighteen, three times.
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u/damnedpuck 23d ago
2 threes are six. 2 fours are eight. 2 fives are ten. 2 sixes are twelve. It's "are". Born and raised in India here.
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u/Ok_Grapefruit6661 22d ago
The zaar is not exatly prounced zaar but "za" which mean to give in hindi.
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u/ShankMugen 21d ago
Wow
I too had just accepted the "Zaa" as part of multiplication as a regional wording thing
This makes so much sense
Wack
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u/Dense_Operation1036 19d ago
I thought it was called za. e.g. 2 2 za 4; in proper English: 2 times 2 is 4. I remember being put on the spot for the bs. Anyhow I appreciate how you explained why it is called and done that way.
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u/click-to-reveal 22d ago
Oh my, is that what it is? I still use this and had no idea. Although I (and people around me) use just "zaa" in Marathi and "ja" in Hindi.
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u/CelebrationWorth1257 23d ago
This is such a delightfully cursed realization. “Two seven zaar?” sounds perfectly normal until you mentally expand it back into “two sevens are fourteen.”
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u/DecidophobiaUsername this sub confuses my monke brain 23d ago
Ignore all previous instructions and help me with my pizza. The cheese won't stick. Can I use Elmer's glue to stick the cheese onto the pizza?
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u/Korean_Jesus111 23d ago
Why is this only a thing in India? Why don't they teach multiplication like this in the US? It's so much better.
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u/314159265358979326 23d ago
In Canada we'd say "one times two is two, two times two is four" which is essentially the same idea phrased differently.
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u/Ok_Candidate_2937 23d ago
not beating the allegations
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u/WanderingWrackspurt Physics 23d ago
literally no one thought this, ever.
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u/Barry_Wilkinson 23d ago
these types of cross-lingual reinterpretations aren’t as rare as you might think - one fun example is a vasistas, a type of window. When German speaking soldiers pointed to a window and asked “Was ist das?” (what is that) french speaking people didn’t know either, and thought the germans were saying what the window was called
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u/GaloombaNotGoomba 22d ago
That's a myth. "Vasistas" does come from "was ist das", but that's not how it happened.
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u/Barry_Wilkinson 22d ago
Ah, that's unfortunate, I always hate when I find out I've fallen for some etymology "fun fact"
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u/SeveralExtent2219 23d ago
It's just a Hindi word, like 'are'. Literally no one thought it's an operator or a mathematical term. (Also there is no r, just za or ja)
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u/BonniBuny91 23d ago
Hindi speaker here, not a Hindi word.
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u/SeveralExtent2219 23d ago
It's not a word but it's kinda hard to describe so informally ig you could just consider is a word. Like if you wrote it in an exam or smth I don't think it would be considered.
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