Frohe Weihnachten, Happy Holidays, Merry Christmas!
I would like to wish everybody a very merry Christmas, happy holidays, and a great 2015!
Frohe Weihnachten und einen guten Rutsch in ein besonders tolles 2015!
And for the mathematically inclined, shown above is a (4,9)-torus knot on the torus
(r-2)^2 + z^2 = 1
(in cylindrical coordinates). The knot has 9 crossings, as you can see from the side view below. I created the image in
Mathematica with the following parametrization:
x = (2 + cos (9t) ) cos (4t),
y = (2 + cos (9t) ) sin (4t),
z = sin (9t).