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Detta verk har gjorts tillgänglig som public domain av dess skapare, David Eppstein på engelska Wikipedia. Detta gäller globalt. I vissa länder kan detta inte vara juridiskt möjligt; i så fall: David Eppstein ger envar rätten att använda detta verk för alla ändamål, utan några villkor, förutom villkor som lagen ställer.Public domainPublic domainfalsefalse

Source code

The Python source code for generating this image:

from math import log

limit = 400
radius = 17
margin = 4
xscale = yscale = 128
skew = 0.285

def A051037():
    yield 1
    seq = [1]
    spiders = [(2,2,0,0),(3,3,0,1),(5,5,0,2)]
    while True:
        x,p,i,j = min(spiders)
        if x != seq[-1]:
            yield x
            seq.append(x)
        spiders[j] = (p*seq[i+1],p,i+1,j)

def nfactors(h,p):
    nf = 0
    while h % p == 0:
        nf += 1
        h //= p
    return nf

seq = []
for h in A051037():
    if h > limit:
        break
    seq.append((h,nfactors(h,2),nfactors(h,3),nfactors(h,5)))

leftmost = max([k for h,i,j,k in seq])
rightmost = max([j for h,i,j,k in seq])
leftwidth = int(0.5 + log(5) * leftmost * xscale + radius + margin)
rightwidth = int(0.5 + log(3) * rightmost * xscale + radius + margin)
width = leftwidth + rightwidth
height = int(0.5 + log(limit) * yscale + 2*(radius + margin))

def place(h,i,j,k):
    # logical coordinates
    x = j * log(3) - k * log(5) + i * skew
    y = log(h)
    
    # physical coordinates
    x = (x*xscale) + leftwidth
    y = (-y*yscale) + height - radius - margin
    
    return (x,y)

print '''<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg xmlns="http://www.w3.org/2000/svg" version="1.1" width="%d" height="%d">''' % (width,height)

print '    <g style="fill:none;stroke:#ffaaaa;">'

l = 1
base = 1
while l <= limit:
    y = -yscale*log(l) + height - radius - margin
    print '        <path d="M0,%0.2fL%d,%0.2f"/>' % (y,width,y)
    l += base
    if l == 10*base:
        base = l

print "    </g>"
print '    <g style="fill:none;stroke-width:1.5;stroke:#0000cc;">'

def drawSegment(p,q):
    x1,y1=p
    x2,y2=q
    print '        <path d="M%0.2f,%0.2fL%0.2f,%0.2f"/>' % (x1,y1,x2,y2)

for h,i,j,k in seq:
    x,y = place(h,i,j,k)
    if i > 0:
        drawSegment(place(h//2,i-1,j,k),(x,y))
    if j > 0:
        drawSegment(place(h//3,i,j-1,k),(x,y))
    if k > 0:
        drawSegment(place(h//5,i,j,k-1),(x,y))

print "    </g>"
print '    <g style="fill:#ffffff;stroke:#000000;">'

for h,i,j,k in seq:
    x,y = place(h,i,j,k)
    print '        <circle cx="%0.2f" cy="%0.2f" r="%d"/>' % (x,y,radius)

# pairs of first value with size: size of that value
fontsizes = {1:33, 5:30, 10:27, 20:24, 100:20, 200:18}

for h,i,j,k in seq:
    x,y = place(h,i,j,k)
    if h in fontsizes:
        print "    </g>"
        print '    <g style="font-family:Times;font-size:%d;text-anchor:middle;">' % fontsizes[h]
        lower = fontsizes[h] / 3.
    print '        <text x="%0.2f" y="%0.2f">%d</text>' %(x,y+lower,h)
print "    </g>"
print "</svg>"

Ursprunglig uppladdningslogg

• 2007-03-14 05:08 David Eppstein 1363×809×0 (13167 bytes) A [[Hasse diagram]] of [[divisibility]] relationships among [[regular number]]s up to 400. Inspired by similar diagrams in a paper by Kurenniemi [http://www.beige.org/projects/dimi/CSDL2.pdf].