In this paper, the eigenvalues of row-inverted 2 × 2 Sylvester Hadamard matrices are derived. Especially when the sign of a single row or two rows of a 2×2 Sylvester Hadamard matrix are inverted, its eigenvalues are completely evaluated. As an example, we completely list all the eigenvalues of 256 different row-inverted Sylvester Hadamard matrices of size 8. Mathematics Subject Classification (...

In this paper, firstly, new Hermite-Hadamard type inequalities for harmonically convex functions in fractional integral forms are given. Secondly, Hermite-Hadamard-Fejer inequalities for harmonically convex functions in fractional integral forms are built. Finally, an integral identity and some Hermite-Hadamard-Fejer type integral inequalities for harmonically convex functions in fractional int...

There are characteristics of Hadamard matrices that enable an exhaustive search using algorithmic techniques. The search derives primarily from the eigenvalues which are constant after the Hadamard matrix is multiplied by its transpose. Generally this would be a performance concern but there are additional properties that enable the eigenvalues to be predicted. Here an algorithm is given to obt...

A recursive method of A. C. Mukhopadhay is used to obtain several new infinite classes of Hadamard matrices. Unfortunately none of these constructions give previously unknown Hadamard matrices of order <40,000. Disciplines Physical Sciences and Mathematics Publication Details Seberry, J, Some infinite families of Hadamard matrices, J Austral Math Soc, Ser. A, 29, 1980, 235-242. This journal art...

In this paper, we propose two new construction methods for quaternary Hadamard matrices. By the first method, which is applicable for any positive integer n, we are able to construct a quaternary Hadamard matrix of order 2 from a binary sequence with ideal autocorrelation. The second method also gives us a quaternary Hadamard matrix of order 2 from a binary extended sequence of period 2 − 1, wh...

The automorphism group of any Hadamard matrix of order n acts on the set of cell co-ordinates {(i, j) | i, j = 1, 2, . . . , n}. Let f(n) denote the least number of cell orbits amongst all the Hadamard matrices of order n. This paper describes Hadamard matrices with a small number of cellwise orbits, and in particular proves some results about the function f . We show that, except possibly for ...

By using the (generalized) Goethals-Seidel array, we construct Hadamard matrices of skew type of order 4n for n = 81,103,151,169, and 463. Hadamard matrices of skew type for these orders are constructed here for the first time. Consequently the list of odd integers n < 300 for which no Hadamard matrix of skew type of order 4n is presently known is reduced to 45 numbers (see the comments after t...

A new construction of complex Hadamard matrices of composite order d = pq, with primes p, q, is presented which is based on pairs of mutually unbiased bases containing only product states. We illustrate the method for many product dimensions d < 100 by analytically deriving complex Hadamard matrices, both with zero and non-zero defect. In particular, we obtain at least 12 new isolated Butson-ty...