Hadamard matrices

In Ian Stewart's book "Die letzten Rätsel der Mathematik" (ISBN 978-3499616945), at the end there is a section about Hadamard matrices. That inspired me to develop a 3D model for the first 12 matrices (of edge length 2, 4, 8, 12, ... 44).

The article https://arxiv.org/html/2411.18897v1 describes in detail how to compute the matrices with SageMath. Online you can run https://sagecell.sagemath.org/ with the following program:

from sage.combinat.matrices.hadamard_matrix import hadamard_matrix, skew_hadamard_matrix

for i in range(1,12):

  H = hadamard_matrix(4*i)

  print(i, "========")

print(H.str())

The output can be reduced with:

perl -pe "s{\-1}{\.}g; s{[\[\]\|\+\-]}{}g; s{\A\s+\Z}{};" infile > outfile