Primes and Squares

El'endia Starman

01:53

@DJMcMayhem ...you're joking, right?

ASCII-only

02:06

@DJMcMayhem :| where have you been for the past few months

@DJMcMayhem infinite? the numbers just have to be coprime I think? unless that's not what you mean (this is probably the case)

DJMcMayhem

03:01

@El'endiaStarman Unfortunately no

@ASCII-only ... Which numbers? We're talking about Cartesian coordinates

quartata

03:22

@DJMcMayhem I'm assuming he means that m and n are coprime for a given (m,n)

El'endia Starman

04:01

@DJMcMayhem You've missed their videos posted by the feed bot for several months?

ASCII-only

05:08

@DJMcMayhem delta-x and delta-y

DJMcMayhem

@El'endiaStarman I mostly lurk in here, and I haven't paid any attention to the feeds tbh

@ASCII-only That makes sense. So infinite

ASCII-only

@DJMcMayhem yeah. well, really if one of delta-x or delta-y is one, that's already an infinite number I think?

> feels

DJMcMayhem

Oi

@ASCII-only Wait, so (0, 0) can hit every point on (1, y) or (x, 1)

(and negative one obviously)

ASCII-only

05:25

yeah. in the square thing i guess it would translate into the number of bounces on opposite walls (assuming it doesn't bounce off the other two rows)?

DJMcMayhem

@ASCII-only Does that necessarily translate though? That proves there's an infinite number of ways the assassin come reflect it to hit himself, but not necessarily an infinite number of ways to hit T

ASCII-only

@DJMcMayhem no, i mean bounces while traveling from A to T

(well, actually that's exactly what it would be if you collapsed/folded/whatever the lattice back into the square, I think)

@DJMcMayhem hang on. isn't this equivalent to O(1)

DJMcMayhem

(at first I thought you were still talking about lattices and I was very confuzzled)

@ASCII-only For certain values of 1, yes

Nathan Merrill

11:28

The assassin puzzle is infinite.

You can generate an infinite number of rays by bouncing against the vertical walls N times

(If the two points are vertical to each other, then you bounce off of horizontal walls N times)

Nathan Merrill

11:53

Language idea: Concatenating strings is an expensive operation

However, often times, you aren't concatenating and doing other operations at the same time

So, if somebody concats two strings, you internally hold them both until they get printed/index of/etc

this means that I could concat many strings together, and get O(n) performance

El'endia Starman

16:26

Lazy concatenation, then. Huh, neat.

Nathan Merrill

actualy...if you're just doing iteration, you don't even need to concat them at all

the only time concatenation becomes important is with random access (substring)

although, you likely would need to do it for printing to the terminal

I have no idea how that works, but I imagine it's a system call that says "print this memory from here to here"

El'endia Starman

Actually, you could use mathematical tricks to simply substring the relevant string parts.

Nathan Merrill

maybe, but you'd have to keep an array of offsets

El'endia Starman

Probably still computationally cheaper, I think.

Nathan Merrill

actually, an array of lengths

I do know that typically with substring you want to copy

like, Java previously had simply referenced the old array on a substring operation

but what happened is that people would have massive strings, and substring a small part out

and so you'd have a huge amount of memory stored for a few characters

so, they decided to copy

El'endia Starman

16:37

People Are Stupid: Exhibit 24702

Nathan Merrill

I mean...there's no good way around it

El'endia Starman

(Well, I mean, there are legitimate cases for doing stuff like that.)

Nathan Merrill

like, it's not intuitive to say "new String(otherString.substring(1,2))"

I personally think that that choice is a hard one: do you copy or reference?

you could do both, but then you have to do detection, and you can no longer reliably know whether an array is referenced

Anyways, with a chunked string, you have a similar problem: The chunks may be smaller

but you still have to decide whether to copy/reference

oooh...you could rechunk a string

nvm, that's just copying

Now, totally different question: What composition of matter is needed for a star?

Like, if I got a whole bunch of say, Carbon, and made a ball the size of the sun, would it still become a star (performing fusion, emitting light?)

like, I know Fusion is Hydrogen based, but would it still theoretically work with other matter?

El'endia Starman

I initially considered a snarky answer saying "A lot." but then realized that yeah, it depends on what it is. If all you have is iron, then you're going to get a black hole before you get a star.

Stellar nucleosynthesis

Stellar nucleosynthesis is the theory explaining the creation (nucleosynthesis) of chemical elements by nuclear fusion reactions between atoms within the stars. Stellar nucleosynthesis has occurred continuously since the original creation of hydrogen, helium and lithium during the Big Bang. It is a highly predictive theory that today yields excellent agreement between calculations based upon it and the observed abundances of the elements. It explains why the observed abundances of elements in the universe grow over time and why some elements and their isotopes are much more abundant than others...

Nathan Merrill

...I can't believe that there's an article about this

like, Helium fusion? Why have I never heard of this?

El'endia Starman

16:50

I think that yes, you could in theory build a star out of carbon; it just wouldn't last very long.

Nathan Merrill

it also appears that the heavier the element, the less energy produced

El'endia Starman

High Mass Stars: Crash Course Astronomy #31

►

^ That's when/where I learned about this.

Nathan Merrill

Carbon-burning process

The carbon-burning process or carbon fusion is a set of nuclear fusion reactions that take place in the cores of massive stars (at least 8 M ⊙ {\displaystyle {\begin{smallmatrix}M_{\odot }\end{smallmatrix}}} at birth) that combines carbon into other elements. It requires high temperatures (> 5×108 K or 50 keV) and...

if the star is between 8-11 solar masses, it'll be a quick flash :)

Huh, so it sounds like stars will burn element by element

going from lightest to heaviest

but how far they make it depends on the mass of the star

eventually they will go cold

El'endia Starman

If the star is small enough, that is.

Nathan Merrill

right, below black-hole size

El'endia Starman

16:57

A huge star can burn e.g. neon, which means really high temperatures and therefore a lot of outward pressure. Once the neon gets used up, then that outward pressure can't balance or stop the gravitational contraction. Which means super compact and super super hot, so kaboom you get a supernova!

(The core that doesn't get blasted apart/away is what becomes a black hole.)

flawr

17:36

@El'endiaStarman but usually you try to somehow convey the important parts e.g. that two lines are parallel or two angles are equal. I remember when they made a logarithm curve that intersected (0,0) or things like that. I agree that it doesn't have to be perfect, but qualitative errors like these just feel so wrong. And in this case these aren't some hand drawn back of the envelope drawings, but stuff they made on a computer...

@Feeds this proves ∞ = 65

@NathanMerrill I'm not gonna make a comment about haskell :P

^ consider the difference between the of the base element and of the product. This is why fusion and decay both "stop" in the neighbourhood of lead or iron.

you should also read about the shell burning processes of stars, a very interesting topics. Also when you consider the speeds of those "shells" and shockwaves that can be generated:)

betseg

18:09

Fe56 has the highest binding energy?

2 * 4th magic number

(magic number)

Nathan Merrill

18:59

@flawr I actually have no idea how strings in haskell work

is it a linked list of characters?

or an array?

flawr

yep basically a linked list, but I was thinking of the lazy evaluation feature:)

flawr

19:44

cool idea for a visualization: youtube.com/watch?v=MZnGvyOuluw

El'endia Starman

@flawr That's really cool.

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