$\mathcal{H}$-Matrix approximation for the operator exponential with applications |
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Authors: | Ivan P Gavrilyuk Wolfgang Hackbusch Boris N Khoromskij |
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Institution: | (1) Berufsakademie Thüringen, Am Wartenberg 2, 99817 Eisenach, Germany; e-mail: ipg@ba-eisenach.de , DE;(2) Max-Planck-Institute for Mathematics in Sciences, Inselstr. 22–26, 04103 Leipzig, Germany; e-mail: {wh,bokh}@mis.mpg.de , DE |
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Abstract: | Summary. We develop a data-sparse and accurate approximation to parabolic solution operators in the case of a rather general elliptic
part given by a strongly P-positive operator 4].
In the preceding papers 12]–17], a class of matrices (-matrices) has been analysed which are data-sparse and allow an approximate matrix arithmetic with almost linear complexity.
In particular, the matrix-vector/matrix-matrix product with such matrices as well as the computation of the inverse have linear-logarithmic
cost. In the present paper, we apply the -matrix techniques to approximate the exponent of an elliptic operator.
Starting with the Dunford-Cauchy representation for the operator exponent, we then discretise the integral by the exponentially
convergent quadrature rule involving a short sum of resolvents. The latter are approximated by the -matrices. Our algorithm inherits a two-level parallelism with respect to both the computation of resolvents and the treatment
of different time values. In the case of smooth data (coefficients, boundaries), we prove the linear-logarithmic complexity
of the method.
Received June 22, 2000 / Revised version received June 6, 2001 / Published online October 17, 2001 |
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Keywords: | Mathematics Subject Classification (1991): 65F50 65F30 15A09 15A24 15A99 |
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