Hadamard matrices: Difference between revisions
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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). | 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). | ||
===Raw data=== | |||
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: | 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: | ||
<code>from sage.combinat.matrices.hadamard_matrix import hadamard_matrix, skew_hadamard_matrix</code> | <code>from sage.combinat.matrices.hadamard_matrix import hadamard_matrix, skew_hadamard_matrix</code> | ||
for i in range(1,12): | |||
H = hadamard_matrix(4*i) | |||
print(i, "========") | |||
print(H.str()) | |||
The output can be reduced with: | The output can be reduced with: | ||
perl -pe "s{\-1}{\.}g; s{[\[\]\|\+\-]}{}g; s{\A\s+\Z}{};" infile > outfile | |||
===3D Design=== | |||
Since the edge lengths increase by 4, solid blocks of bxwxh = 1x1x2 will be used to represent a one in a matrix plane, and empty space for a zero (resp. -1). The matrix planes will be stacked as a pyramid, with the 44x44 matrix at the bottom and the 4x4 at the top. Maybe the 2x2 matrix becomes the real top, maybe with blocks 1x1x1? |
Latest revision as of 20:44, 19 July 2025
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).
Raw data
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
3D Design
Since the edge lengths increase by 4, solid blocks of bxwxh = 1x1x2 will be used to represent a one in a matrix plane, and empty space for a zero (resp. -1). The matrix planes will be stacked as a pyramid, with the 44x44 matrix at the bottom and the 4x4 at the top. Maybe the 2x2 matrix becomes the real top, maybe with blocks 1x1x1?