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2 votes
0 answers
204 views

Finding specific coefficients of product of high-dimensional Fourier series faster than FFT

I need a fast algorithm to perform a specific Fourier-type computation in my physics research. Suppose I have the following two Fourier series in three dimensions $$ a(t_1,t_2,t_3)=\sum_{j=-n}^{n}\...
groupoid's user avatar
  • 620
1 vote
0 answers
168 views

Circulant matrix inverse in $GF(p)$

For a polynomial $C(x)=c_0+\dots+c_n x^n$, consider a circulant matrix $C$ such that $$ C= \begin{pmatrix} c_0 & c_{n-1} & \cdots & c_2 & c_1 \\ c_1 & c_0 &...
Oleksandr  Kulkov's user avatar
3 votes
0 answers
93 views

Efficient multiplication of Cayley-Dickson numbers

The question was already asked here, but doesn't have any meaningful answer, hence I'd like to re-post it. Assuming that we have an algebra with conjugation, we can use Cayley-Dickson construction to ...
Oleksandr  Kulkov's user avatar
3 votes
0 answers
155 views

Why does division parallelize but not continued fractions and is there an analog of multiplication to continued fractions?

All the basic arithmetic operations $\times,+,/,-$ can be parallelized. However continued fraction representation of a rational number is not parallelized. The process of Euclid's algorithm looks ...
Turbo's user avatar
  • 13.9k
3 votes
1 answer
77 views

Level sums, displacements: how to determine them efficiently?

Let $R =\mathbb{Z}/N \mathbb{Z}$. Let $f:R\to \mathbb{R}$, $\rho:R\to \lbrack 0,1\rbrack$. We assume that it takes trivial time to compute any given value $f(m)$ or $\rho(m)$. Define $$S(\delta,m) = ...
H A Helfgott's user avatar
  • 20.2k