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Determination of eigenvalues and eigenvectors by means of iterations of subspaces

100%

Pokrzywa A.

Mathematica Applicanda

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1985

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tom 12

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nr 24

PL

.

EN

Let A be a compact linear operator in a Banach space X. The author investigates the iterations of a given subspace M of X. He formulates sufficient conditions for the convergence (in the sense of the gap between subspaces). This result is applied to the study of spectra of operators.

2

Spectra of approximating operators

100%

Pokrzywa A.

Mathematica Applicanda

|

1995

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tom 24

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nr 38

PL

.

EN

This is an interesting expository article about the approximation of operators on a complex infinite-dimensional Hilbert space. Although the article does not include research published during the past twenty years or so, it provides a nice account of the stability of the spectrum under approximation (or perturbation). The reader interested in pursuing this area of research might refer to the bibliography in [D. A. Herrero, Approximation of Hilbert space operators. Vol. I, Pitman, Boston, MA, 1982; MR0676127] and the subsequent publications of those authors.

3

Matrices splitting the norm and their applications in the theory of stability of difference schemes

100%

Pokrzywa A.

Mathematica Applicanda

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1985

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tom 13

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nr 26

PL

.

EN

In a finite-dimensional real or complex linear normed space X there are characterized all the sets of operators A1,...,An which sum up to the identity operator and such that ||Aix||+...+||Anx|=||x|| for all xX. An example of application in the theory of stability of difference schemes is given.

4

Perturbation of the spectrum οf an essentially selfadjoint operator

100%

Pokrzywa A.

Applicationes Mathematicae

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1993-1995

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tom 22

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nr 1

75-89

EN

The aim of this paper is to find estimates of the Hausdorff distance between the spectra of two nonselfadjoint operators. The operators considered are assumed to have their imaginary parts in some normed ideal of compact operators. In the case of the classical Schatten ideals the estimates are given explicitly.

5

On an infinite-dimensional version of the Kreiss matrix theorem

100%

Pokrzywa A.

Banach Center Publications

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1994

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tom 29

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nr 1

45-50

6

Correction to "Method od orthogonal projections and approximation of the spectrum of a bounded operator" Studia Math. 65 (1979), 21-29

75%

Pokrzywa A.

Studia Mathematica

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1985

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tom 81

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nr 3

341

7

Sur les systèmes infinis d'équations différentielles ordinaires dans certains espaces de Fréchet

69%

Moszyński K., Pokrzywa A.

Instytut Matematyczny Polskiej Akademii Nauk

EN

Table des Matières § 1. Généralités. Matrices infinies............................................ 5 § 2. Systèmes infinis d'équations différentielles. Problème de Cauchy. Existence- unicité............................................................................ 10 § 3. Approximation par les systèmes finis......................................... 20 § 4. Dépendance de la solution des conditions initiales ou d'un paramètre......... 23 § 5. Quelques remarques sur la séparation des variables........................... 25 Les ouvrages cités................................................................. 32

8

Method of orthogonal projections and approximation of the spectrum of a bounded operator II

44%

Pokrzywa A.

Studia Mathematica

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1981

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tom 70

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nr 1

1-9

9

Method of orthogonal projections and approximation of the spectrum of a bounded operator

44%

Pokrzywa A.

Studia Mathematica

|

1979

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tom 65

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nr 1

21-29

Ograniczanie wyników

3 Mathematica Applicanda

3 Studia Mathematica

1 Applicationes Mathematicae

1 Banach Center Publications

9 Pokrzywa A.

1 Moszyński K.

1 1995

1 1994

1 1993

3 1985

1 1981

1 1979

1 1974

Determination of eigenvalues and eigenvectors by means of iterations of subspaces

Spectra of approximating operators

Matrices splitting the norm and their applications in the theory of stability of difference schemes

Perturbation of the spectrum οf an essentially selfadjoint operator

On an infinite-dimensional version of the Kreiss matrix theorem

Correction to "Method od orthogonal projections and approximation of the spectrum of a bounded operator" Studia Math. 65 (1979), 21-29

Sur les systèmes infinis d'équations différentielles ordinaires dans certains espaces de Fréchet

Method of orthogonal projections and approximation of the spectrum of a bounded operator II

Method of orthogonal projections and approximation of the spectrum of a bounded operator