File:Non-Desargues configuration.svg
Summary
| Description |
English: A 103 configuration that is not incidence-isomorphic to a Desargues configuration. Redrawn more accurately from a bitmap image by Michael Hardy, Pentagrams.png. |
| Date | |
| Source |
Own work based on: Pentagrams.png:  by Michael Hardy |
| Author | David Eppstein |
| SVG development |
Source code
This image was created as a pdf file by the following Python code, then recolored in Adobe Illustrator and converted to SVG.
from pyx import canvas,path,color
from math import *
rot = [e**(pi*0.4j*i) for i in range(5)]
def orient(p,q):
return p.real * q.imag - p.imag * q.real
def testx(x):
p = rot[1].real + 1j * x
return orient(p - 1, p * rot[3] - 1)
lo,hi = 3,4
while hi - lo > 1e-8:
mid = (lo+hi)/2.0
if testx(mid) < 0: hi = mid
else: lo = mid
c = canvas.canvas()
scale=2.0
def edge(p,q):
c.stroke(path.line(p.real*scale,p.imag*scale,q.real*scale,q.imag*scale),
[color.rgb.black])
def point(p):
c.fill(path.circle(p.real*scale,p.imag*scale,0.08*scale),[color.rgb.red])
for i in range(5):
p2 = 1 * rot[i-4]
p3 = (rot[1].real + 1j * mid) * rot[i]
p4 = p3 * rot[2]
edge(p3,p4)
edge(p4,p2)
for i in range(5):
point(1*rot[i])
point((rot[1].real + 1j * mid) * rot[i])
c.writePDFfile("Non-Desargues configuration")
Licensing
 |
I, the copyright holder of this work, release this work into the public domain. This applies worldwide. In some countries this may not be legally possible; if so: I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law. |
