98,973 research outputs found
Multi-dimensional real Fourier transform
Four subroutines compute one-dimensional and multi-dimensional Fourier transforms for real data, multi-dimensional complex Fourier transforms, and multi-dimensional sine, cosine and sine-cosine transforms. Subroutines use Cooley-Tukey fast Fourier transform. In all but one-dimensional case, transforms are calculated in up to six dimensions
Fast Quantum Fourier Transforms for a Class of Non-abelian Groups
An algorithm is presented allowing the construction of fast Fourier
transforms for any solvable group on a classical computer. The special
structure of the recursion formula being the core of this algorithm makes it a
good starting point to obtain systematically fast Fourier transforms for
solvable groups on a quantum computer. The inherent structure of the Hilbert
space imposed by the qubit architecture suggests to consider groups of order
2^n first (where n is the number of qubits). As an example, fast quantum
Fourier transforms for all 4 classes of non-abelian 2-groups with cyclic normal
subgroup of index 2 are explicitly constructed in terms of quantum circuits.
The (quantum) complexity of the Fourier transform for these groups of size 2^n
is O(n^2) in all cases.Comment: 16 pages, LaTeX2
Fast Fourier Transforms for Finite Inverse Semigroups
We extend the theory of fast Fourier transforms on finite groups to finite
inverse semigroups. We use a general method for constructing the irreducible
representations of a finite inverse semigroup to reduce the problem of
computing its Fourier transform to the problems of computing Fourier transforms
on its maximal subgroups and a fast zeta transform on its poset structure. We
then exhibit explicit fast algorithms for particular inverse semigroups of
interest--specifically, for the rook monoid and its wreath products by
arbitrary finite groups.Comment: ver 3: Added improved upper and lower bounds for the memory required
by the fast zeta transform on the rook monoid. ver 2: Corrected typos and
(naive) bounds on memory requirements. 30 pages, 0 figure
Fast Fourier Transforms for the Rook Monoid
We define the notion of the Fourier transform for the rook monoid (also
called the symmetric inverse semigroup) and provide two efficient
divide-and-conquer algorithms (fast Fourier transforms, or FFTs) for computing
it. This paper marks the first extension of group FFTs to non-group semigroups
Efficient Quantum Transforms
Quantum mechanics requires the operation of quantum computers to be unitary,
and thus makes it important to have general techniques for developing fast
quantum algorithms for computing unitary transforms. A quantum routine for
computing a generalized Kronecker product is given. Applications include
re-development of the networks for computing the Walsh-Hadamard and the quantum
Fourier transform. New networks for two wavelet transforms are given. Quantum
computation of Fourier transforms for non-Abelian groups is defined. A slightly
relaxed definition is shown to simplify the analysis and the networks that
computes the transforms. Efficient networks for computing such transforms for a
class of metacyclic groups are introduced. A novel network for computing a
Fourier transform for a group used in quantum error-correction is also given.Comment: 30 pages, LaTeX2e, 7 figures include
Composite Cyclotomic Fourier Transforms with Reduced Complexities
Discrete Fourier transforms~(DFTs) over finite fields have widespread
applications in digital communication and storage systems. Hence, reducing the
computational complexities of DFTs is of great significance. Recently proposed
cyclotomic fast Fourier transforms (CFFTs) are promising due to their low
multiplicative complexities. Unfortunately, there are two issues with CFFTs:
(1) they rely on efficient short cyclic convolution algorithms, which has not
been investigated thoroughly yet, and (2) they have very high additive
complexities when directly implemented. In this paper, we address both issues.
One of the main contributions of this paper is efficient bilinear 11-point
cyclic convolution algorithms, which allow us to construct CFFTs over
GF. The other main contribution of this paper is that we propose
composite cyclotomic Fourier transforms (CCFTs). In comparison to previously
proposed fast Fourier transforms, our CCFTs achieve lower overall complexities
for moderate to long lengths, and the improvement significantly increases as
the length grows. Our 2047-point and 4095-point CCFTs are also first efficient
DFTs of such lengths to the best of our knowledge. Finally, our CCFTs are also
advantageous for hardware implementations due to their regular and modular
structure.Comment: submitted to IEEE trans on Signal Processin
Fast Computation of Voigt Functions via Fourier Transforms
This work presents a method of computing Voigt functions and their
derivatives, to high accuracy, on a uniform grid. It is based on an adaptation
of Fourier-transform based convolution. The relative error of the result
decreases as the fourth power of the computational effort. Because of its use
of highly vectorizable operations for its core, it can be implemented very
efficiently in scripting language environments which provide fast vector
libraries. The availability of the derivatives makes it suitable as a function
generator for non-linear fitting procedures.Comment: 8 pages, 1 figur
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