Fox Talbot's Theorem
FoxTalbot:=proc()
local q,L,i,a,b,c,j,M:
for i from 1 to 5 do
L[i]:=a[i]*x+b[i]*y+c[i]:
od:
for i from 1 to 5 do
Concurrent(seq(M[i],i=1..5)):
end:
#Added July 31, 2006: Dick Tahta told us that this theorem
is really due to Olry Terquem (1845)
q:=Quad
(seq(L[j],j=1..i-1),seq(L[j],j=i+1..5)):
M[i]:=
Le(
MidPt(q[1],q[3]) ,
MidPt(q[2],q[4])):
od: