The Experts below are selected from a list of 90 Experts worldwide ranked by ideXlab platform

Hong Qin - One of the best experts on this subject based on the ideXlab platform.

  • VEST: Abstract vector calculus simplification in Mathematica ☆
    Computer Physics Communications, 2014
    Co-Authors: Jonathan Squire, Joshua W. Burby, Hong Qin
    Abstract:

    Abstract We present a new package, VEST (Vector Einstein Summation Tools), that performs abstract vector calculus computations in Mathematica. Through the use of index notation, VEST is able to reduce three-dimensional scalar and vector expressions of a very general type to a well defined standard form. In addition, utilizing properties of the Levi-Civita Symbol, the program can derive types of multi-term vector identities that are not recognized by reduction, subsequently applying these to simplify large expressions. In a companion paper Burby et al. (2013)  [12] , we employ VEST in the automation of the calculation of high-order Lagrangians for the single particle guiding center system in plasma physics, a computation which illustrates its ability to handle very large expressions. VEST has been designed to be simple and intuitive to use, both for basic checking of work and more involved computations. Program summary Program title: VEST (Vector Einstein Summation Tools) Catalogue identifier: AEQN_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEQN_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 10469 No. of bytes in distributed program, including test data, etc.: 72539 Distribution format: tar.gz Programming language: Mathematica. Computer: Any computer running Mathematica. Operating system: Linux, Unix, Windows, Mac OS X. RAM: Usually under 10 Mbytes Classification: 5, 12, 19. Nature of problem: Large scale vector calculus computations Solution method: Reduce expressions to standard form in index notation, automatic derivation of multi-term vector identities. Restrictions: Current version cannot derive vector identities without cross products or curl Additional comments: Intuitive user input and output in a combination of vector and index notation Running time: Reduction to standard form is usually less than one second. Simplification of very large expressions can take much longer.

  • VEST: Abstract vector calculus simplification in Mathematica ☆
    Computer Physics Communications, 2014
    Co-Authors: Jonathan Squire, Joshua W. Burby, Hong Qin
    Abstract:

    We present a new package, VEST (Vector Einstein Summation Tools), that performs abstract vector calculus computations in Mathematica. Through the use of index notation, VEST is able to reduce three-dimensional scalar and vector expressions of a very general type to a well defined standard form. In addition, utilizing properties of the Levi-Civita Symbol, the program can derive types of multi-term vector identities that are not recognized by reduction, subsequently applying these to simplify large expressions. In a companion paper (Burby et al., 2013), we employ VEST in the automation of the calculation of high-order Lagrangians for the single particle guiding center system in plasma physics, a computation which illustrates its ability to handle very large expressions. VEST has been designed to be simple and intuitive to use, both for basic checking of work and more involved computations.Comment: Accepted for publication in Computer Physics Communication

Jonathan Squire - One of the best experts on this subject based on the ideXlab platform.

  • VEST: Abstract vector calculus simplification in Mathematica ☆
    Computer Physics Communications, 2014
    Co-Authors: Jonathan Squire, Joshua W. Burby, Hong Qin
    Abstract:

    Abstract We present a new package, VEST (Vector Einstein Summation Tools), that performs abstract vector calculus computations in Mathematica. Through the use of index notation, VEST is able to reduce three-dimensional scalar and vector expressions of a very general type to a well defined standard form. In addition, utilizing properties of the Levi-Civita Symbol, the program can derive types of multi-term vector identities that are not recognized by reduction, subsequently applying these to simplify large expressions. In a companion paper Burby et al. (2013)  [12] , we employ VEST in the automation of the calculation of high-order Lagrangians for the single particle guiding center system in plasma physics, a computation which illustrates its ability to handle very large expressions. VEST has been designed to be simple and intuitive to use, both for basic checking of work and more involved computations. Program summary Program title: VEST (Vector Einstein Summation Tools) Catalogue identifier: AEQN_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEQN_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 10469 No. of bytes in distributed program, including test data, etc.: 72539 Distribution format: tar.gz Programming language: Mathematica. Computer: Any computer running Mathematica. Operating system: Linux, Unix, Windows, Mac OS X. RAM: Usually under 10 Mbytes Classification: 5, 12, 19. Nature of problem: Large scale vector calculus computations Solution method: Reduce expressions to standard form in index notation, automatic derivation of multi-term vector identities. Restrictions: Current version cannot derive vector identities without cross products or curl Additional comments: Intuitive user input and output in a combination of vector and index notation Running time: Reduction to standard form is usually less than one second. Simplification of very large expressions can take much longer.

  • VEST: Abstract vector calculus simplification in Mathematica ☆
    Computer Physics Communications, 2014
    Co-Authors: Jonathan Squire, Joshua W. Burby, Hong Qin
    Abstract:

    We present a new package, VEST (Vector Einstein Summation Tools), that performs abstract vector calculus computations in Mathematica. Through the use of index notation, VEST is able to reduce three-dimensional scalar and vector expressions of a very general type to a well defined standard form. In addition, utilizing properties of the Levi-Civita Symbol, the program can derive types of multi-term vector identities that are not recognized by reduction, subsequently applying these to simplify large expressions. In a companion paper (Burby et al., 2013), we employ VEST in the automation of the calculation of high-order Lagrangians for the single particle guiding center system in plasma physics, a computation which illustrates its ability to handle very large expressions. VEST has been designed to be simple and intuitive to use, both for basic checking of work and more involved computations.Comment: Accepted for publication in Computer Physics Communication

Friedrich W. Hehl - One of the best experts on this subject based on the ideXlab platform.

  • premetric teleparallel theory of gravity and its local and linear constitutive law
    European Physical Journal C, 2018
    Co-Authors: Yakov Itin, Yuri N. Obukhov, Jens Boos, Friedrich W. Hehl
    Abstract:

    We continue to investigate the premetric teleparallel theory of gravity (TG) with the coframe (tetrad) as gravitational potential. We start from the field equations and a local and linear constitutive law. We create a Tonti diagram of TG in order to disclose the structure of TG. Subsequently we irreducibly decompose the 6th order constitutive tensor under the linear group. Moreover, we construct the most general constitutive tensors from the metric and the totally antisymmetric Levi-Civita Symbol, and we demonstrate that they encompass nontrivial axion and skewon type pieces. Using these tools, we derive for TG in the geometric-optics approximation propagating massless spin 0, 1, and 2 waves, including the special case of Einstein’s general relativity.

Joshua W. Burby - One of the best experts on this subject based on the ideXlab platform.

  • VEST: Abstract vector calculus simplification in Mathematica ☆
    Computer Physics Communications, 2014
    Co-Authors: Jonathan Squire, Joshua W. Burby, Hong Qin
    Abstract:

    Abstract We present a new package, VEST (Vector Einstein Summation Tools), that performs abstract vector calculus computations in Mathematica. Through the use of index notation, VEST is able to reduce three-dimensional scalar and vector expressions of a very general type to a well defined standard form. In addition, utilizing properties of the Levi-Civita Symbol, the program can derive types of multi-term vector identities that are not recognized by reduction, subsequently applying these to simplify large expressions. In a companion paper Burby et al. (2013)  [12] , we employ VEST in the automation of the calculation of high-order Lagrangians for the single particle guiding center system in plasma physics, a computation which illustrates its ability to handle very large expressions. VEST has been designed to be simple and intuitive to use, both for basic checking of work and more involved computations. Program summary Program title: VEST (Vector Einstein Summation Tools) Catalogue identifier: AEQN_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEQN_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 10469 No. of bytes in distributed program, including test data, etc.: 72539 Distribution format: tar.gz Programming language: Mathematica. Computer: Any computer running Mathematica. Operating system: Linux, Unix, Windows, Mac OS X. RAM: Usually under 10 Mbytes Classification: 5, 12, 19. Nature of problem: Large scale vector calculus computations Solution method: Reduce expressions to standard form in index notation, automatic derivation of multi-term vector identities. Restrictions: Current version cannot derive vector identities without cross products or curl Additional comments: Intuitive user input and output in a combination of vector and index notation Running time: Reduction to standard form is usually less than one second. Simplification of very large expressions can take much longer.

  • VEST: Abstract vector calculus simplification in Mathematica ☆
    Computer Physics Communications, 2014
    Co-Authors: Jonathan Squire, Joshua W. Burby, Hong Qin
    Abstract:

    We present a new package, VEST (Vector Einstein Summation Tools), that performs abstract vector calculus computations in Mathematica. Through the use of index notation, VEST is able to reduce three-dimensional scalar and vector expressions of a very general type to a well defined standard form. In addition, utilizing properties of the Levi-Civita Symbol, the program can derive types of multi-term vector identities that are not recognized by reduction, subsequently applying these to simplify large expressions. In a companion paper (Burby et al., 2013), we employ VEST in the automation of the calculation of high-order Lagrangians for the single particle guiding center system in plasma physics, a computation which illustrates its ability to handle very large expressions. VEST has been designed to be simple and intuitive to use, both for basic checking of work and more involved computations.Comment: Accepted for publication in Computer Physics Communication

Yakov Itin - One of the best experts on this subject based on the ideXlab platform.

  • premetric teleparallel theory of gravity and its local and linear constitutive law
    European Physical Journal C, 2018
    Co-Authors: Yakov Itin, Yuri N. Obukhov, Jens Boos, Friedrich W. Hehl
    Abstract:

    We continue to investigate the premetric teleparallel theory of gravity (TG) with the coframe (tetrad) as gravitational potential. We start from the field equations and a local and linear constitutive law. We create a Tonti diagram of TG in order to disclose the structure of TG. Subsequently we irreducibly decompose the 6th order constitutive tensor under the linear group. Moreover, we construct the most general constitutive tensors from the metric and the totally antisymmetric Levi-Civita Symbol, and we demonstrate that they encompass nontrivial axion and skewon type pieces. Using these tools, we derive for TG in the geometric-optics approximation propagating massless spin 0, 1, and 2 waves, including the special case of Einstein’s general relativity.