The Nineteenth Byte

user

12:44 AM

@DLosc Yeah, Scala's static typing definitely makes it more verbose, but I feel like the big standard library kinda makes up for it once you wrap your head around it

You really only have to deal with Seqs, Lists, Sets, and Maps (and occasionally Arrays if you split a String)

OldSandboxPosts

1:00 AM

Sandbox posts last active a week ago: Can you draw this in one stroke

DLosc

1:11 AM

LYAL time?

Aiden Chow

@DLosc which one is it

DLosc

6 hours ago, by DLosc

Looks like either Desmos or Haskell, provided somebody is around who can teach one of those

Aiden Chow

@DLosc OH

ok so i do desmos

DialFrost

i do none :(

DLosc

@AidenChow Excellent!

Aiden Chow

1:15 AM

@DLosc so how does this work again

do i just teach desmos stuff or what?

and do i have to start it right now?

DLosc

Yeah, start with a quick intro of How to Desmos, and then post small challenges that can be solved in Desmos and give people tips as they try to solve them. The event runs for 24 hours, so you don't have to start right now if you're not available at the moment.

Aiden Chow

@DLosc how long do i have to be on for those 24 hrs

like if im not on most of the time, is that ok

DialFrost

wats LYAL

Aiden Chow

15

Q: Language nominations for the "Learn You a Lang for Great Good" chat event

We've decided we'd like to give the "Learn You a Lang for Great Good" chat event \${}^*\$ a go. As a brief overview, this event would be: For around an hour (or as long as participants want) every two weeks Every second Wednesday, discussion in The Nineteenth Byte is primarily about a specific p...

DLosc

@AidenChow However much time you want to. Don't neglect your real-life responsibilities. ;) It's less an issue of Have To and more an issue of being active encourages people to participate.

DialFrost

1:19 AM

oh

Aiden Chow

@DLosc do i have to register here: chat.stackexchange.com/rooms/info/240/…

is there some special place i do it

like another chat room??

DLosc

Nope, we have it here and the recurring, currently running event is the event

I'll post an official "start of LYAL" message in a minute, which will probably get pinned by the mods

Aiden Chow

@DLosc palms starting to sweat lol

impromptu time XD

DLosc

It's very laid back usually :)

Aiden Chow

@DLosc okay

DialFrost

1:23 AM

i need to learn a new lang any recommendations=

Aiden Chow

@DialFrost Desmos ;)

DialFrost

lol

DLosc

Welcome to the fourteenth (I think) Learn You A Lang for Great Good! Today, we'll be learning Desmos, an online graphing calculator that can also be used for code golf. During the event, feel free to post CMCs to practice Desmos, ask questions about the language, and so on.

8

Aiden Chow

ok that is my cue lmao

so before we start, i just want to clear any confusion by saying that we are only working with the desmos graphing calculator on this website: desmos.com/calculator

as opposed to the other tools that desmos has made, like the matrix calculator

in desmos, "code" is represented as a set of equations/expressions

as opposed to some of the more popular languages, there isnt really an order that each expression/equation is calculated, so no need to worry about that

Unrelated String

are there generally no side effects then?

Aiden Chow

1:30 AM

@UnrelatedString yes, if you swap the order of the equations, there should generally be no side effects

Unrelated String

are you aware of anything that does have side effects

Aiden Chow

as it is a graphing calculator, you can expect that desmos supports many basic arithmetic operators

@UnrelatedString hmmm lemme think

not that i am aware of, though i may be horribly wrong

usually i just write code that makes intuitive sense even when ran in the "correct" order

anyways, things such as +, -, / should all work as you expect them to

factorials too

DialFrost

yo yo yo aidenchow chill ur godspeeding desmos rn :P

Aiden Chow

i want to talk about the equal sign next. in desmos, it has two main functions.

@DialFrost lol just want to get out as much info as i can before i have to leave :D

the first is that it acts like an assignment operator, similar to what you expect when initiating variables in something like python

on the left, you can put either a variable name, like a, b, c, etc., or a function, f(x), g(x), a(x), etc.

on the right, an expression

this will set the variable/function to the expression

DialFrost

um @DLosc u understanding any of this

DLosc

1:38 AM

@DialFrost Yup, I'm tracking

DialFrost

wow i dont understanding anything XD

DLosc

It helps to have Desmos open and play around with typing stuff to see what happens

Aiden Chow

oh, i forgot to mention. all desmos expressions are represented in raw text as LaTeX

anyways, note that variable names cannot have a number in it, unless if it is in a subscript

so you cant do 1a=1, but you can do a_1=1.

lyxal

That's news to me

All these years of desmos and I never knew that

Aiden Chow

@lyxal uhhh ok, cant tell if thats sarcasm or not lol

DialFrost

1:41 AM

lmao

Unrelated String

presumably specifically the bit about subscripts

lyxal

@AidenChow it's not

Unrelated String

since that wouldn't come up a ton in the course of normal graphing

lyxal

I genuinely didn't know you could have subscript numbers in variable names

DialFrost

@AidenChow isnt this like python variables

@lyxal still cant tell if thats sarcasm XD

lyxal

1:42 AM

@DialFrost not sarcasm

Aiden Chow

@DialFrost yeah a bit, except variable names cannot have more than one letter that is not part of a subscript

so ab_1 is not a valid variable name

but something like v_{alid} is

for functions, they can be split into two parts: their name, and their arguments

much like a mathematical function, it is in the form name(arguments)

the name of a function pretty much follows the exact same rules that variable names follow

lyxal

@AidenChow wait it is?

How deep can subscript nesting go?

Aiden Chow

@lyxal lemme test right now

uh seems like i cant go past one subscript

Unrelated String

f

Aiden Chow

cant type it in, lemme try pasting the LaTeX in directly

nope, gives an error

so something like v_{v_v} doesnt work

ok going back to functions

also similar to mathematical functions, you can define arguments with different "variables", which follow the same naming conventions as regular variables

DialFrost

1:48 AM

u sound like u created desmos my guy XD

Aiden Chow

so something like f_1(a_1,a_2,a_3,a_4) is a valid function initialization

@DialFrost im sure other people are way more experienced in desmos than i am

DialFrost

u sound pretty experienced urself :P

Aiden Chow

ahem fireflame241 ahem

DialFrost

whos that

Aiden Chow

@DialFrost reddit.com/user/fireflame241

DialFrost

1:50 AM

?

Aiden Chow

also a fellow code golf user

fireflame241

14.6k 2 23 70

code-golf math string decision-problem number sequence grid

Unrelated String

was about to say isn't that someone's username here

DialFrost

lol

Aiden Chow

yeah, hes like 10 times more experienced in desmos than me. he helps me golf my desmos code from time to time

DialFrost

ok hes an expection ur the 2nd most experience then :P

Aiden Chow

1:52 AM

ok back to desmos functions

on the right of the equals sign, you can set a function equal to an expression in terms of its arguments, which you can then reuse the function as you need to

functions are also my preferred method of I/O, mainly because it is easy to test the code

@DialFrost nah i dont think so, have you seen the ppl in the desmos discord?

DialFrost

uh no i rarely go to dc nowadays

Aiden Chow

the graphs that they make are literally insane

DialFrost

im sure u can do the same :)

Aiden Chow

@DialFrost nah, i only specialize in desmos code golf, not graph making

DialFrost

graph making isnt terribly hard

desmos code golf is tricky to learn in the first place

DLosc

1:56 AM

Then let's learn some now :P

Aiden Chow

@DLosc ya true :D

DialFrost

i can learn fast but i forget fast and get bored fast

Aiden Chow

i want to now introduce arguably the most important data type in desmos, the list

DialFrost

unless i rly rly rly focus which nvr rly happens

oh sry pls continue aiden :/

Aiden Chow

a list is constructed using a pair of brackets, with comma separated expressions/numbers in between

for example, [2,3,4,1,6] would be a list

another example: if variables a, b, and c are defined, then [a,b,c] is also a list

you can also construct a list using ranges, which will automatically fill the list with numbers in the range

this can be done using 3 dots ...

for example, [1...5] will construct the list [1,2,3,4,5]

you can even construct a range which is decrementing, like [5...1]

that is the same as [5,4,3,2,1]

Unrelated String

2:01 AM

ooh, and it also looks like you can do steps that way

Aiden Chow

you can also specify the common difference (or how much its going to increment/decrement each time) of the range

Unrelated String

like [1,3...11]

Aiden Chow

@UnrelatedString yep :) i was just going to talk about that

like the example @UnrelatedString gave, you can supply the second element of the range, which will specify the step of the range

the number that the list ends with does not have to be in the range. if that happens, then the range stops at the number right before it goes past the last number

that might be a bit confusing, so heres an example: [1,3...10]

if you keep incrementing by 2 from 1, you wont get to 10 exactly

oops i said that a bit wrong

it should be "the number right after it goes past the last number"

so in this case, 11 is the number that is reached following the range, so the list that is constructed is the same as [1,3...11]

to get a specific element from a list, you can do list[index], where index is the index of the element you are accessing

desmos is 1-indexed, so index values start at 1, not 0

oh crap i should probably do some mini questions right?

i totally forgot i had to do those

Unrelated String

also it seems like you can use listy expressions inside the indexing brackets to slice? and/or just sort of map over the indexing list to index into the indexed list

Aiden Chow

@UnrelatedString yes, thats true

you can essentially index a list with another list, and it will create a sort of mapping

ok whats the acronym for chat questions again?

Unrelated String

2:12 AM

cmc

Aiden Chow

@UnrelatedString thanks

Unrelated String

lyals usually theme the acronym based on the language

like they replace the chat with the language's name

Aiden Chow

what does cmc stand for ?

Unrelated String

chat mini challenge

so this would be a desmos mini challenge, which would be a...
dmc

Aiden Chow

so i replace "chat" with "desmos"?

okay

Unrelated String

2:14 AM

cue devil may cry soundtrack

Aiden Chow

DMC: create a function f that takes in three arguments, and returns the average of those 3 arguments.

rip no one answer, okay

what about

DMC: create a function f that takes in a list of numbers l and returns l but with every other element removed. the first element of l should always be kept in the output.

Unrelated String

f(a,b,c)=(a+b+c)/3? feels like there ought to be a way to skip one of those parens but maybe not

Aiden Chow

@UnrelatedString yep, thats basically it. im not aware of a way to shorten that

Unrelated String

i'll put my answer to the second one in a tio link since it might be worth not spoiling but i'm not aware of a way to actually link to it on desmos lol

tio.run/##K85JLM5ILf7/P00jR9M2J9pQx1hPTy/2/38A

maybe the trailing bracket can be dropped

it can

Aiden Chow

@UnrelatedString it cant: desmos.com/calculator/iqrxxs0zbt

@UnrelatedString looking at this just made me realize that i forgot to mention that if you dont supply an ending number of a range when indexing, it is assumed to end at the length of the list that is being indexed

so [1,6,5,4][2...] would actually just be [1,6,5,4][2...4]

hmm lemme think if im missing something before moving on

ok cant think of anything rn

next i want to talk about how arithmetic with lists is handled in desmos

in desmos, most operations are handled similar to arithmetic on vectors

in that it applies an operator by pairing the corresponding elements of each list

when thinking about arithmetic with lists, i like to think about it like a for loop. for each list's first element, compute the expression. that will be the first element of the resulting list. for each lists' second element, compute the expression. that will be the second element, and son on

with this way of thinking, the for loop would only run up until the loop goes through all the elements of the shortest list in the computation

ok im talking to no one rn lol

lyxal

2:50 AM

Wait desmos vectorises stuff automatically?

Cool

Newly Featured Posts

12

Q: Convert a string of ASCII characters to base-3 equivalents

Task similar to this one. Take a string of ASCII characters and convert it to base-3 equivalents separated by a space. For example: Hello, world! Should be converted to 02200 10202 11000 11000 11010 01122 01012 11102 11010 11020 11000 10201 01020 The output should only contain numbers with the ...

code-golf string base-conversion

Sandbox Posts

3:10 AM

0

A: Sandbox for Proposed Challenges

Fibonacci triangle Given an integer n, output the following ASCII art to n rows: 1+1=2 1+2=3 2+3=5 3+5=8 5+8=13 Essentially, the first row is 1+1=2 and the nth row (1-indexed) is \$f_n + f_{n+1} = f_{n+2}\$ where \$f\$ is the Fibonacci sequence, padded so the numbers line up ...

Radvylf Programs

Ah yes, because the White House is very famously under Republican leadership right now...

Thanks YT

emanresu A

The white house has a youtube channel???

Newly Featured Posts

3:23 AM

20

Q: Is given number a concat of two squares

Given a positive integer, determine if it can be represented as a concatenation of two square numbers. Concatenated numbers may not begin with 0 (except for 0). Any leading zeros in input should be ignored. Examples 11 -> true // because 1 and 1 are squares 90 -> true // because 9 and 0 are squ...

code-golf decision-problem integer

Unrelated String

@AidenChow for some reason the keystrokes seem to let you drop the trailing bracket but if you copy paste it breaks (and you can't even balance it with a keystroke afterwards; the unbalanced bracket renders smaller than it would normally and if you try to type a close bracket afterwards it auto-balances an open bracket at the start of the line)

Radvylf Programs

In order to be differentiable a function has to be continuous, right?

mfw

emanresu A

My calculus course included proof by induction

lyxal

I remember doing that

I also remember forgetting that

@RadvylfPrograms that's right

emanresu A

Which involved verifying multiple-choice proofs

and doing that a lot.

DLosc

3:30 AM

@RadvylfPrograms GOP response (short rebuttal speech from a Republican after the president's speech)

Radvylf Programs

Oh, does that happen?

DLosc

Yep. The opposite party picks someone to deliver their response each year.

It's televised, but it's not delivered at the capitol

lyxal

Can't wait to see Bad Lip Reading's version of the state of the union this year

DLosc

@RadvylfPrograms Gotta remember those piecewise functions. Think of f(x) = x+7 if x <= 1, x+3 if 1 < x < 4, and x-11 if 4 <= x.

Radvylf Programs

That's not differentiable, is it?

I've always been told continuity is a requirement for differentiability

DLosc

3:36 AM

It's differentiable on the interval 1 < x < 4 (constant slope of 1 over that interval b/c over that interval it's defined as x+3 which is continuous).

The question didn't say it was differentiable everywhere.

Radvylf Programs

Well as long as it's differentiable on that interval, it's also continuous on that interval. There's no reason to care about anything outside of 1 < x < 4 for this question.

DLosc

In a sense, but then you have to ignore the information about the points f(1)=8 and f(4)=-7 because those are outside the interval 1 < x < 4 too.

Unrelated String

oh yeah because you could have discontinuities at the ends of the open interval it's differentiable over

Radvylf Programs

Hmm. I guess so, although that seems incredibly minor

emanresu A

Infinitesimally, actually

But it still matters

Unrelated String

3:40 AM

they probably want to make sure you're careful with your intervals

DLosc

What it boils down to is that the only thing you know about the function on that open interval is that it's continuous and differentiable and f(2) = 5. It could be a constant f(x) = 5 for all 1 < x < 4. Or it could be f(x) = x^5 - 27. So you can't apply the mean value theorem and you really can't conclude anything about the slope.

If you knew it was differentiable on 1 <= x <= 4, different story.

Radvylf Programs

Yeah, I get it

PyGamer0

oh we are learning demsocks

cool

unfortunately i have to go to school

Radvylf Programs

The explanation should definitely have put more emphasis on the interval though, since that's what it seems to be trying to teach us to pay attention to

Unrelated String

italicizing the word closed would probably have been a good idea since they italicized cannot already

user

3:45 AM

Why is your teacher not explaining this themselves?

Radvylf Programs

Because there's 160 problems and it's self-paced

emanresu A

ಠ_ಠ Do you have anyone you can ask for help?

(aside from us)

user

Lol I’m happy i don’t go to your school

Radvylf Programs

@emanresuA There's a tutorial video for every problem that goes over a similar one

user

Sounds like they have no teachers and y’all just do everything yourselves

Radvylf Programs

3:47 AM

@user It's a review for all of AB

user

You should try taking BC, it’s single var and not too hard

Radvylf Programs

I'm taking BC

emanresu A

Same lol

Radvylf Programs

This is a review of the AB stuff

user

Oh ok

emanresu A

3:48 AM

I'm almost done though

user

Good luck to both of you

Radvylf Programs

I'm kinda surprised integration by parts is BC stuff...like, "hey AB kids, here's how to integrate, but to do it for more stuff, you'll need Integration Pro™ for only $1.99"

PyGamer0

protip: use desmos for math homework, its TC.

Radvylf Programs

Contip: You can't use desmos on the AP test, and if you're used to having desmos, you won't do well

user

Wolfram Alpha and Geogebra better

Wolfram and Symbolab can solve all sorts of stuff and geogebra has 3d graphing

PyGamer0

3:50 AM

protip: since calculators arent technically allowed, technically programming languages are ...

emanresu A

@RadvylfPrograms Yeah, integration by parts is very useful

Radvylf Programs

Idea: Replace the Z80 on a TI calculator with a raspberry pi

Even better, one of the fancy TI-84 CEs that have a color screen

user

Idwa: spread covid everywhere so the test becomes virtual so you can cheat

lyxal

> The massages do not need to be persistently stored on server.

emanresu A

College Board issues aside, I have fond memories of TI-BASIC, writing in it a 3D graphing engine and a stock market analyzer. With enough patience, I could make anything ... but friends. (Although with my chatterbot experiments, I certainly tried.)

PyGamer0

3:52 AM

i have virtual final exams from 28th this month

user

You know you can make your own apps and programs for the ti right?

Radvylf Programs

Yeah, but the Z80 is slow and has no WiFi

PyGamer0

write your exam on the TI

Radvylf Programs

A full Linux install on a TI calculator would be so OP on tests

(A full Linux install that runs at close to useful speeds, that is)

PyGamer0

you can just ... use a search engine

user

3:54 AM

How?

Radvylf Programs

In an in-person exam?

user

can’t sneak it in

PyGamer0

install one on the TI

user

Uhhh

Radvylf Programs

Doesn't have WiFi by default

or any way to display HTML

user

3:54 AM

how you gonna download wifi lol

emanresu A

Get a calculator case and put a cheap phone in it

user

@PyGamer0 good luck, remember that cheating is always an option

@emanresuA it meeds to look convincing when you type too

The entire body needs to look like a Ti

This would actually be an interesting project

Radvylf Programs

And an original TI screen would be way more convincing and cool

user

How would you make it so the keys go to your pi instead of wherever they’re supposed to go?

DLosc

@RadvylfPrograms Sounds like AB and BC ~= Calc I and II from my experience. If so, I just assumed it's divided up that way because integration is complicated and there's just not as much material to cover with differentiation.

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