Abstract
The convergence of columns in the univariateqd-algorithm to reciprocals of polar singularities of meromorphic functions has often proved to be very useful. A multivariateqd-algorithm was discovered in 1982 for the construction of the so-called homogeneous Padé approximants.
In the first section we repeat the univariate convergence results. In the second section we summarize the “homogeneous” multivariateqd-algorithm. In the third section a multivariate convergence result is proved by combining results from the previous sections. This convergence result is compared with another theorem for the general order multivariateqdg-algorithm. The main difference lies in the fact that the homogeneous form detects the polar singularities “pointwise” while the general form detects them “curvewise”.
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References
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A. Cuyt,The qd-algorithm and multivariate Padé approximants, Numer. Math., 42 (1983), pp. 259–269.
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P. Henrici,Applied and Computational Complex Analysis I, J. Wiley, New York, 1974.
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Cuyt, A. On the convergence of the multivariate “homogeneous”qd-algorithm. BIT 34, 535–545 (1994). https://doi.org/10.1007/BF01934266
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DOI: https://doi.org/10.1007/BF01934266