Top #numbertheory dweets

function u(t) {

c.width=1920 // clear the canvas
for(i=0;i<9;i++)
x.fillRect(400+i*100+S(t)*300,400,50,200) // draw 50x200 rects

} // 122/140

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    u(t) is called 60 times per second.
    t: Elapsed time in seconds.
    S: Shorthand for Math.sin.
    C: Shorthand for Math.cos.
    T: Shorthand for Math.tan.
    R: Function that generates rgba-strings, usage ex.: R(255, 255, 255, 0.5)
    c: A 1920x1080 canvas.
    x: A 2D context for that canvas.

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donbright

remix of d/15061 by u/taupelink

function u(t) {

t||(a=[],s=r=k=0)
J=s-r+k
x.fillStyle=R(a[s+k]=k%r?a[J]+a[J-1]:1,a[J-1],a[J-2])
r<99&&x.fillRect(1e3-8*r+16*k,8*r+8,8,8)
++k>r&&(s+=++r,k=0)

Jul 24 2019 3:51 PM UTC

}// 140/140

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Pascal's funky triangle

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taupelink

function u(t) {

t||(a=[[]],r=k=0);x.font=`3em"`
a[r][k]=k%r?a[r-1][k-1]+a[r-1][k]:1
r<16&&x.fillText(a[r][k],960-60*r+120*k,60*r+60)
++k>r&&(a[++r]=[],k=0)

Jun 18 2019 1:17 AM UTC

}// 139/140

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Pascal's Triangle #math #recursive #recursion

u/katkip

Awesome!
u/donbright

#numbertheory

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taupelink

function u(t) {

c.width|=0;f=X=>{for(i=2;i*i<=X;i++)if(X%i==0)return i+'*'+f(X/i);return X};k=frame/6|0;x.font='5em"';x.fillText(k+'='+f(k),0,540)

Jun 28 2019 1:01 AM UTC

}// 130/140

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factorization into #prime products. #math

u/taupelink

simple #recursion #recursive
u/Xen

very clever
u/katkip

wow
u/donbright

#numbertheory

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taupelink

function u(t) {

t||(x.font=`30em"`,x.fillText("1+",40,620),x.fillText("1",1050,400),x.fillRect(570,b=450,1200,24))
x.drawImage(c,0,0,2e3,1e3,650,b,1100,550)

Jul 24 2019 3:24 AM UTC

}// 140/140

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Continued fraction for the golden ratio, 1+sqrt(5)/2. #math #numbertheory https://en.wikipedia.org/wiki/Golden_ratio

u/taupelink

hmm, doesn't seem to work on iOS Safari
u/taupelink

to get it to work on iOS/MacOS, replace 2e3 with 1920 and 1100 with 1e3.
u/taupelink

* maybe it's a safari issue rather than an OS issue. * on my iOS device, that adjustment seems to work temporarily, but then the browser has to reload the screen. ¯\_(ツ)_/¯

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donbright

remix of d/1871 by u/walsh9

function u(t) {

圈=(n,d,N,D)=>{d+D<15?(圈(n,d,n+N,d+D),圈(n+N,d+D,N,D),w=2e3,m=d+D,x.beginPath(),r=w/m/m/2,x.arc(w*(n+N)/m,r,r,0,7),x.fill()):1}
圈(0,1,1,1)

Mar 7 2017 11:35 PM UTC

}// 136/140

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basic Ford's Circles (sort of like Apollonian Circle Packing but every circle touches the floor, or here, the ceiling)

u/donbright

#math
u/donbright

see also https://www.dwitter.net/d/15086 by @taupelink
u/donbright

#numbertheory
u/taupelink

nice!

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jellyedwards

function u(t) {

t/k>2?k+=++j:x.translate((c.width|=b=τ/j)/2,h=500)
t&1?d+=b/120:x.scale(1,C(t*τ))
for(a=d;τ>a-d;x.fill())x.arc(0,0,h,a+=b,a)}{j=k=3,d=τ=6.28

Nov 20 2020 6:48 AM UTC

}// 140/140

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Group #symmetry #numbertheory

u/jellyedwards

Trying to do this sort of thing for all polygons: http://mathonline.wikidot.com/the-group-of-s…
u/jellyedwards

Not much point posting this when there are mountain landscapes and stargates dweets around lol
u/smtsjhr

i can appreciate these Dihedral Group symmetries
u/DataMeta

interesting! glad you posted it :)

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taupelink

remix of d/15085 by u/taupelink

function u(t) {

t||(A=[e=512,e+1],r=i=n=2);i--?(z=A[i],N=z%e,D=z>>9,x.fillText(N+'/'+D,N/D*1900,D*9),n-i-1&&A.splice(i+1,0,w+z),w=z):(i=n+=n-1)

Jul 22 2019 12:55 AM UTC

}// 127/140

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Farey sequence #math #numbertheory

u/donbright

awesome
u/IV

called Farey because wings? :)

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taupelink

function u(t) {

f=j=>x.fillRect(448+(j&255)*4,(j>>8)*4,4,4)
t||(p=Array(N=4**8).fill(n=1),f(0),f(1))
if(p[++n])for(i=1;(q=++i*n)<N;)p[q]=0,f(q),M=n;throw M

Jun 19 2019 2:39 AM UTC

}// 139/140

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Sieve of Eratosthenes. Throws primes less than 65536. Row Y Column X stays unfilled if 256*Y+X is prime. #math

u/Xen

clever
u/donbright

#primes #numbertheory
u/taupelink

maybe #sieve is a worthwhile hashtag too!

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taupelink

function u(t) {

f=(a,b,n)=>b?(a>=b?
(x.fillStyle=R(25*n),
x.fillRect(X,Y,b,b),X+=d?0:b,Y+=d?b:0,f(a-b,b,n+1))
:(d=!d,f(b,a,n+1))
):0
d=X=Y=0;f(1920,1080,0)

Jun 13 2019 1:58 AM UTC

}// 139/140

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GCD(1920,1080)=120, the size of the smallest reddest square. Demonstration of Euclidean algorithm by subtraction, cf. https://en.wikipedia.org/wiki/Euclidean_algo… #math

u/taupelink

#recursive #recursion
u/taupelink

(120 is the side length, not the size)
u/donbright

#numbertheory
u/donbright

this is super interesting

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taupelink

function u(t) {

t||(c.width=162,r=X=4567,s=Y=89,h=l=n=1,i=k=0)
r&&x.fillText(h+`x${X}+(${k})x${Y}=`+r,0,n++*9),q=r/s|0,[h,k,r,i,l,s]=[i,l,s,h-q*i,k-q*l,r%s]

Jul 1 2019 4:45 AM UTC

}// 140/140

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Extended Euclidean algorithm, to find h, k such that hX+kY=gcd(X,Y) #math #numbertheory

u/durian-favored-monster

i remember this in high school it was very cool! good job! this is the best text one i've seen
u/geb

EEA is so cool!

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