The Experts below are selected from a list of 26145 Experts worldwide ranked by ideXlab platform
Eric Polizzi - One of the best experts on this subject based on the ideXlab platform.
-
feast as a subspace iteration eigensolver accelerated by approximate spectral projection
SIAM Journal on Matrix Analysis and Applications, 2014Co-Authors: Ping Tak Peter Tang, Eric PolizziAbstract:The calculation of a segment of eigenvalues and their corresponding eigenvectors of a Hermitian matrix or matrix pencil has many applications. A new density-matrix-based algorithm has been proposed recently and a software package FEAST has been developed. The density-matrix approach allows FEAST's implementation to exploit a key strength of modern computer architectures, namely, multiple levels of parallelism. Consequently, the software package has been well received, especially in the electronic structure community. Nevertheless, theoretical analysis of FEAST has lagged. For instance, the FEAST algorithm has not been proven to converge. This paper offers a detailed numerical analysis of FEAST. In particular, we show that the FEAST algorithm can be understood as an accelerated subspace iteration algorithm in conjunction with the Rayleigh--Ritz procedure. The novelty of FEAST lies in its accelerator, which is a rational matrix function that approximates the spectral projector onto the eigenspace in questio...
-
feast as a subspace iteration eigensolver accelerated by approximate spectral projection
arXiv: Numerical Analysis, 2013Co-Authors: Ping Tak Peter Tang, Eric PolizziAbstract:The calculation of a segment of eigenvalues and their corresponding eigenvectors of a Hermitian matrix or matrix pencil has many applications. A new density-matrix-based algorithm has been proposed recently and a software package FEAST has been developed. The density-matrix approach allows FEAST's implementation to exploit a key strength of modern computer architectures, namely, multiple levels of parallelism. Consequently, the software package has been well received, especially in the electronic structure community. Nevertheless, theoretical analysis of FEAST has lagged. For instance, the FEAST algorithm has not been proven to converge. This paper offers a detailed numerical analysis of FEAST. In particular, we show that the FEAST algorithm can be understood as an accelerated subspace iteration algorithm in conjunction with the Rayleigh-Ritz procedure. The novelty of FEAST lies in its accelerator which is a rational matrix function that approximates the spectral projector onto the eigenspace in question. Analysis of the numerical nature of this approximate spectral projector and the resulting subspaces generated in the FEAST algorithm establishes the algorithm's convergence. This paper shows that FEAST is resilient against rounding errors and establishes properties that can be leveraged to enhance the algorithm's robustness. Finally, we propose an extension of FEAST to handle non-Hermitian problems and suggest some future research directions.
Ping Tak Peter Tang - One of the best experts on this subject based on the ideXlab platform.
-
feast as a subspace iteration eigensolver accelerated by approximate spectral projection
SIAM Journal on Matrix Analysis and Applications, 2014Co-Authors: Ping Tak Peter Tang, Eric PolizziAbstract:The calculation of a segment of eigenvalues and their corresponding eigenvectors of a Hermitian matrix or matrix pencil has many applications. A new density-matrix-based algorithm has been proposed recently and a software package FEAST has been developed. The density-matrix approach allows FEAST's implementation to exploit a key strength of modern computer architectures, namely, multiple levels of parallelism. Consequently, the software package has been well received, especially in the electronic structure community. Nevertheless, theoretical analysis of FEAST has lagged. For instance, the FEAST algorithm has not been proven to converge. This paper offers a detailed numerical analysis of FEAST. In particular, we show that the FEAST algorithm can be understood as an accelerated subspace iteration algorithm in conjunction with the Rayleigh--Ritz procedure. The novelty of FEAST lies in its accelerator, which is a rational matrix function that approximates the spectral projector onto the eigenspace in questio...
-
feast as a subspace iteration eigensolver accelerated by approximate spectral projection
arXiv: Numerical Analysis, 2013Co-Authors: Ping Tak Peter Tang, Eric PolizziAbstract:The calculation of a segment of eigenvalues and their corresponding eigenvectors of a Hermitian matrix or matrix pencil has many applications. A new density-matrix-based algorithm has been proposed recently and a software package FEAST has been developed. The density-matrix approach allows FEAST's implementation to exploit a key strength of modern computer architectures, namely, multiple levels of parallelism. Consequently, the software package has been well received, especially in the electronic structure community. Nevertheless, theoretical analysis of FEAST has lagged. For instance, the FEAST algorithm has not been proven to converge. This paper offers a detailed numerical analysis of FEAST. In particular, we show that the FEAST algorithm can be understood as an accelerated subspace iteration algorithm in conjunction with the Rayleigh-Ritz procedure. The novelty of FEAST lies in its accelerator which is a rational matrix function that approximates the spectral projector onto the eigenspace in question. Analysis of the numerical nature of this approximate spectral projector and the resulting subspaces generated in the FEAST algorithm establishes the algorithm's convergence. This paper shows that FEAST is resilient against rounding errors and establishes properties that can be leveraged to enhance the algorithm's robustness. Finally, we propose an extension of FEAST to handle non-Hermitian problems and suggest some future research directions.
Gábor Barna - One of the best experts on this subject based on the ideXlab platform.
-
Culture of Feasts today. Commemorial rites of national and calendar Feasts
Acta Ethnographica Hungarica, 2011Co-Authors: Gábor BarnaAbstract:The traditional ritual year which was characterized by Christian Feasts for centuries on one hand, and the cosmological, agrarian (economic), individual, family, and local communal holidays on the other, has been rapidly changing between 1945 and 1956 during the first Socialist/Communist years. A new system of the ritual year was established according to the new ideology and power situation: the so-called Socialist ritual year. It was characterized by international, Soviet and national-communist Feasts, refusing the religious holidays. Some softening were introduced only after the 1956 Hungarian revolution. The main Christian Feasts were again accepted (Christmas, Easter). This Socialist period with its Socialist Feasts lasted for 45 years when in 1989/1990 the legal power system was changed.After the elction in 1990 the totalitarian Socialist ideology with its symbolic holidays has mostly disappeared. New national Feasts were created e.g. the memorial day of the 1956 revolution which was a prohibited alt...
Barna Gábor - One of the best experts on this subject based on the ideXlab platform.
-
Culture of Feasts today. Commemorial rites of national and calendar Feasts
'Akademiai Kiado Zrt.', 2031Co-Authors: Barna GáborAbstract:The traditional ritual year which was characterized by Christian Feasts for centuries on one hand, and the cosmological, agrarian (economic), individual, family, and local communal holidays on the other, has been rapidly changing between 1945 and 1956 during the first Socialist/Communist years. A new system of the ritual year was established according to the new ideology and power situation: the so-called Socialist ritual year. It was characterized by international, Soviet and national-communist Feasts, refusing the religious holidays. Some softening were introduced only after the 1956 Hungarian revolution. The main Christian Feasts were again accepted (Christmas, Easter). This Socialist period with its Socialist Feasts lasted for 45 years when in 1989/1990 the legal power system was changed.After the elction in 1990 the totalitarian Socialist ideology with its symbolic holidays has mostly disappeared. New national Feasts were created e.g. the memorial day of the 1956 revolution which was a prohibited alternative feast during the Socialist period. Patriotic holidays have regained their importance. The symbols of the Feasts have been totally changed. The traditional Christian ritual year has been partly restored, but in a rather secularized society. Christmas, Easter have been commercionalized. Local Feasts have emerged which serve first of all the restoration of the civil society and express the local identity.The paper deals with the process of changes in Hungary showing the role of the holidays and the ritual year in society
Ihnat Kati - One of the best experts on this subject based on the ideXlab platform.
-
Orígenes y desarrollo de la fiesta litúrgica de la Virgen María en Iberia
'Editorial CSIC', 2019Co-Authors: Ihnat KatiAbstract:There is a tendency to speak of a special devotion to the Virgin Mary in Visigothic Iberia, on the basis especially of the foundation of a new feast day in her honour. The seventh century nevertheless saw a general development of Marian liturgies in different parts of Mediterranean and Western Europe. In Rome alone, four Marian Feasts were founded, probably around the mid-seventh century, and possibly linked to the Lateran Council of 649 where the doctrine of Mary’s perpetual virginity was officially established. The presence in Rome of Taius, bishop of Zaragoza, raises the possibility that the idea of founding a new Marian feast in Iberia came from outside the Peninsula, as the very legislation founding the feast suggests. This study looks at the beginnings of Marian commemoration in order to integrate the Iberian case into a wider devotional and theological context.Se da por cierta una gran devoción mariana en la Iberia visigoda, especialmente por el establecimiento, en esa época, de una nueva celebración litúrgica en honor a la Virgen María. Sin embargo, el siglo VII conoció un progresivo desarrollo de liturgias marianas en diversas partes del Mediterráneo y de Europa occidental. En Roma se fundaron cuatro fi estas marianas a mediados del siglo VII, posiblemente con motivo del concilió de Letrán del año 649, en el que se declaró oficial la creencia en la perpetua virginidad de María. La presencia en Roma, alrededor de estas fechas, del obispo de Zaragoza, Tajón, hace suponer que el establecimiento de esta festividad mariana en Iberia pudo venir de fuera, tal como sugiere la legislación en torno a ella. Este estudio investiga los comienzos de esta conmemoración mariana con el fin de contextualizar el caso ibérico en el panorama devocional y teológico del momento
