A k x k matrix A = [aU lover a field F is called circulant if aij = a (j-i) mod k' A [2k ,k l linear code over F = GF (q) is called double-circulant if it is generated by a matrix of the fonn [I A l, where A is a circulant matrix. In this work we ftrst employ the Fourier transform techJ nique to analyze and construct se:veral families of double-circulant codes. The minimum distance of the resul...

Note. The determinant of a circulant matrix is an example of a group determinant, where the group is the cyclic group of order n. In 1880 Dedekind suggested generalizing the case of circulants (and more generally group de­ terminants for abelian groups) to arbitrary groups. It was this suggestion that led Frobenius to the creation group of representation theory. See [1] and the references therein.

S ome mathematical topics—circulant matrices, in particular—are pure gems that cry out to be admired and studied with different techniques or perspectives in mind. Our work on this subject was originally motivated by the apparent need of the first author to derive a specific result, in the spirit of Proposition 24, to be applied in his investigation of theta constant identities [9]. Although pr...

In this paper we rst review the basic computational properties of per-manents, and then address some problems concerning permanents of (0; 1) circulant matrices. In particular we analyze their role at the boundary between computational tractability and intractability, showing that (i) a generic circulant matrix contains large arbitrary submatrices, a fact which casts some doubt on the tractabil...

The preconditioned conjugate gradient method is employed to solve Toeplitz systems T n x = b where the generating functions of the n-by-n Toeplitz matrices T n are functions with zeros. In this case, circulant preconditioners are known to give poor convergence, whereas band-Toeplitz preconditioners only ooer linear convergence and can only handle real-valued functions with zeros of even orders....

The permanent of an n x n matrix A = (a;j) is the matrix function ( 1) per A = ∑ al1r(1)••• a .. ",( .. )".C~" where the summation is over all permutations in the symmetric group, S ... An n x n matrix A is a circulant if there are scalars ab ... ,a,. such that (2) A= ∑ a;pi-l where P is the n x n permutation matrix corresponding to the cycle (12• .. n) in s". In general the computation of the ...

In this paper, some properties of circulant partial Hadamard matrices the form \(4-H(k\times 2k)\) have been obtained together with a method construction help Toeplitz matrices.

We present a circulant and skew-circulant splitting (CSCS) iterative method for solving large sparse continuous Sylvester equations AX+XB=C, where the coefficient matrices A B are Toeplitz matrices. theoretical study shows that if factors of positive semi-definite (not necessarily Hermitian), at least one factor is definite, then CSCS converges to unique solution equation. In addition, our anal...

In this paper, we construct self-dual codes from a construction that involves both block circulant matrices and quadratic residue matrices. We provide conditions when can yield codes. of various lengths over F2 F2+uF2. Using extensions, neighbours sequences neighbours, many new particular, one code length 66 51 68.

This note reports work in progress in connection with Ryser’s conjecture on circulant Hadamard matrices.