The voltammetric behaviour of methylmercury at Nafion coated glassy carbon electrodes is examined. Cyclic voltammograms recorded at coated electrodes show a dramatic increase of peak currents with respect to bare electrodes, this effect being more evident in perchlorate supporting electrolytes rather than in chloride containing media. Experimental evidence indicates that ion-exchange preconcent...

Using trigonometric polynomial interpolation, a fast and effective numerical algorithm for computing the inverse of a triangular Toeplitz matrix with real numbers has been recently proposed [Lin et al., Theor Comp Sci 315: 511–523, 2004]. The complexity of the algorithm is two fast Fourier transforms (FFTs) and one fast cosine transform (DCT) of 2n-vectors. In this paper, we present an algorith...

In this paper we discuss architecture-specific performance tuning for fast Fourier transforms (FFTs) implemented in the UHFFT library. The UHFFT library is an adaptive and portable software library for FFTs developed by the authors. We present the optimization methods used at different levels, starting with the algorithm selection used for the library code generation and ending with the actual ...

This paper presents a new algorithm for constructing a complete list of pairwise inequivalent ordinary irreducible representations of a finite solvable group G. The input of the algorithm is a pc-presentation corresponding to a composition series refining a chief series of G. Modifying the Baum-Clausen-Algorithm for supersolvable groups and combining this with an idea of Plesken for constructin...

This paper presents some new results on numerical stability for multivariate fast Fourier transform of nonequispaced data (NFFT). In contrast to fast Fourier transform (of equispaced data), the NFFT is an approximate algorithm. In a worst case study, we show that both approximation error and roundoff error have a strong influence on the numerical stability of NFFT. Numerical tests confirm the t...

In this paper fast Fourier transform algorithms (FFT's) are constructed for wreath products of the form GS n ]. Examples of interest include the hyperoctahedral groups B n (the symmetry groups of the n-cube) as well as more generally AS n ] for any abelian groups A and also the full wreath products S m S n ] and their iterates, often identiied as automorphism groups of spherically homogeneous r...

The relationship between the mode content and the fractional Fourier and fractional Hankel transforms of a function is established. It is shown that the Laguerre-Gauss spectrum of a rotationally symmetric wave front can be determined from the wave front's fractional Hankel transforms taken at the optical axis.

and the inverse Fourier transform is f (x) = 1 2π ∫ ∞ −∞ F(ω)e dω Recall that i = √−1 and eiθ = cos θ+ i sin θ. Think of it as a transformation into a different set of basis functions. The Fourier transform uses complex exponentials (sinusoids) of various frequencies as its basis functions. (Other transforms, such as Z, Laplace, Cosine, Wavelet, and Hartley, use different basis functions). A Fo...

Fast Fourier transform (FFT)-based computations can be far more accurate than the slow transforms suggest. Discrete Fourier transforms computed through the FFT are far more accurate than slow transforms, and convolutions computed via FFT are far more accurate than the direct results. However, these results depend critically on the accuracy of the FFT software employed, which should generally be...