A comparison is made between Pade and Pade -type approximants. Let Q n be the n th orthonormal polynomial with respect to a positive measure + with compact support in C. We show that for functions of the form where w is an analytic function on the support of +, Pade -type approximants with denomina
Toeplitz matrix techniques and convergence of complex weight Padé approximants
✍ Scribed by Alphonse P. Magnus
- Publisher
- Elsevier Science
- Year
- 1987
- Tongue
- English
- Weight
- 981 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0377-0427
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✦ Synopsis
One considers diagonal Pad~ approximants about m of functions of the form
where w is an integrable, possibly complex-valued, function defined on [-1, 1].
Convergence of the sequence of diagonal Pad4 approximants towards f is established under the condition that there exists a weight ~o, positive almost everywhere on [ -1, 1], such that g(x) = w(x)/,o (x) is continuous and not vanishing on [ -1, 1].
The rate of decrease of the error is also described. The proof proceeds by establishing the link between the Pad6 denominators and the orthogonal polynomials related to ~o, in terms of the Toeplitz matrix of symbol g(cos 0).
📜 SIMILAR VOLUMES
Questions related to the convergence problem of diagonal Pad6 approximants are discussed. A central place is taken by the Pad6 Conjecture (also known as the Baker-Gammel-Wills Conjecture). Partial results concerning this conjecture are reviewed and weaker and more special versions of the conjecture
## An extrapolation method based on Yad6approsimants of type II is suggested for general iterative sequences.. Preliminary numerical !es~r indicate illat when the proposed method is applied to Hortree-Fock SCF iterarkc se-qz~nces. a considerable reduction CT the number of iterarions is expected.