A blog of Python-related topics and code.
Visualizing the real forms of the spherical harmonics
Posted by: christian in Featured on frontpage on 15 Jun 2020
The spherical harmonics are a set of special functions defined on the surface of a sphere that originate in the solution to Laplace's equation, $\nabla^2f=0$. Because they are basis functions for irreducible representations of SO(3), the group of rotations in three dimensions, they appear in many scientific domains, in particular as the angular part of the wavefunctions of atoms (atomic orbitals). They are described in terms of an integer degree $l=0,1,2,\ldots$ and order $m=-l,-l+1,\ldots,l$.
Ratios of random numbers
Posted by: christian on 23 May 2020
The last episode of 3Blue1Brown's "lockdown math" series posed the problem: given two numbers, $x$ and $y$, chosen randomly from the uniform distribution between 0 and 1, what is the proportion that their ratio, when rounded down to the nearest integer, is even? That is, what is $P(\lfloor \frac{x}{y} \rfloor \mod 2 = 0)$?
The Babylonian spiral
Posted by: christian in Featured on frontpage on 22 May 2020
A Babyonian spiral (OEIS A256111) is the figure formed by starting with a zero-vector at the origin and concatenating vectors such that each subsequent vector is the next one longer than the previous one that also lands on a position with integral Cartesian coordinates. That is, the $i$th vector has integer components $x_i$ and $y_i$ satisfying, $x_i^2 + y_i^2 = n_i^2 > n_{i-1}^2$. Each vector is chosen such that it minimizes the angular separation from the previous one.
Hexagonal Truchet tiling
Posted by: christian on 28 Apr 2020
Following on from this earlier post, here is a class, TruchetHexes, which generates a pleasing weave-like pattern by tiling the following hexagon shapes in random orientations.
Inflation in Austria
Posted by: christian on 21 Apr 2020
STATISTICS AUSTRIA provides economic and demographic statistical services to the state of Austria. This page lists the Consumer Price Index it calculates every month according to a methodology that is updated every five years.