This article relies too much on references to primary sources . (November 2009) (Learn how and when to remove this template message) |
Original author(s) | Inst. f. Aero- & Gasdynamik (University of Stuttgart) |
---|---|
Initial release | August 1999 |
Stable release | 1.6.7 / April 14, 2009 |
Written in | Fortran, C |
Operating system | all POSIX systems |
Platform | platform independent |
Available in | English / German |
Type | postprocessing, computer file format |
License | MIT License |
Website | wiki |
EAS3 (EAS = Ein-Ausgabe-System) is a software toolkit for reading and writing structured binary data with geometry information and for postprocessing of these data. It is meant to exchange floating-point data according to IEEE standard between different computers, to modify them or to convert them into other file formats. It can be used for all kinds of structured data sets. It is mainly used in the field of direct numerical simulations.
The complete package consists of libraries intended for usage in own codes and a separate command-line tool. It is written in Fortran and C and runs on all POSIX operating systems. The libraries include different numerical algorithms and subroutines for reading and writing files in the binary EAS3 file format. The read/write routines are provided in Fortran and C. Implemented numerical methods include, for example, Fast Fourier transform, Thomas algorithm and interpolation routines. The libraries are also suitable for vector computers.
EAS3 has been developed at the Institut für Aerodynamik und Gasdynamik (IAG) of the University of Stuttgart. The previous versions (EAS, EAS2) range back to the end of the 1980s, when computer power allowed the first spatial DNS computations. [1] The upcoming amount of data required efficient handling and postprocessing. Typically, simulations were, and are still today, performed on a high-performance computer and afterwards postprocessed on other machines of opposite endianness. This required an endianness-independent file format for data handling.
Since the publication of EAS3 in the 1999, the software has been developed continuously by members of the involved institutes. Since 2007, EAS3 is also available via the heise software directory. [2] EAS3 is used by applications within the European PRACE project. [3] The current version number is 1.6.7 from April, 2009.
Filename extension | .eas |
---|---|
Magic number | EAS3_I8R8 |
Developed by | Universität Stuttgart |
Type of format | binary format for floating point data |
The EAS3 file format is used to store floating point data in IEEE format and to exchange the files between different computer architectures (little/big endian). The data is organized as parameters with one parameter being a one-, two- or three-dimensional floating point array. Several of these parameters may be combined to one time step. This allows to store five-dimensional arrays. Data can be written in single-precision (32 Bit), double-precision (64 Bit) or quadruple-precision (128 Bit). Geometry information for the different directions are saved in the header of the file. It is also possible to store additional information in user defined arrays there. With the file size being limited only by the computer itself (e.g. file system), EAS3 files are suitable for large simulations and thus for high-performance computing. [4] [5]
The actual EAS3 executable is a command-line interface for alteration of EAS3 files. The implemented commands range from basic operations, e.g. simple computations, file operations, to rather complex operations like Fourier transformation or the computation of derivatives. Specific commands for DNS data are also available, e.g. the lambda2 vortex criterion. As the commands are read from standard input, EAS3 may be used in shell scripts for automated calls.
Outline of important functions
The sources can be obtained directly from the CVS repository or one may download a zipped tar file. Makefiles for different machine types are included, providing an easy compilation. As linking of object files, created with different Fortran compilers can cause problems, binary packages (RPM, .deb) are not offered up to now.
The main profit for the programmer is the easy implementation of reading/writing large (>2GB) binary data sets. The library provides that the data is always written big endian. The resulting platform independence allows data exchange between different hardware architectures, e.g. supercomputers. The users benefits from the different methods provided for postprocessing, which can be automated using shell scripts.
Being specialized on structured grids may be a problem for some users. Up to now, only cartesian grids or a representation of the data in spectral space are implemented. Data in other types of data alignment, e.g. cylindrical coordinates, can be stored in EAS3 files but the existing postprocessing commands may not be used. As the usually used visualization programs do not support the EAS3 file format directly, it is often necessary to convert the data to the corresponding file format. Commands in the EAS3 program are given by a text interface, a graphical user interface does not exist. Completion of the commands in the EAS3 command line provides support for interactive usage but for an extensive help, the descriptions on the webpage are necessary.
EAS3 is published under the MIT License. The MIT License is a free software license originating at the Massachusetts Institute of Technology (MIT). Specifically, it is a GPL-compatible permissive license, meaning that it permits reuse within proprietary software on the condition that the license is distributed with that software.
Fortran is a general-purpose, compiled imperative programming language that is especially suited to numeric computation and scientific computing.
In computing, floating-point arithmetic (FP) is arithmetic using formulaic representation of real numbers as an approximation to support a trade-off between range and precision. For this reason, floating-point computation is often used in systems with very small and very large real numbers that require fast processing times. In general, a floating-point number is represented approximately with a fixed number of significant digits and scaled using an exponent in some fixed base; the base for the scaling is normally two, ten, or sixteen. A number that can be represented exactly is of the following form:
In computing, endianness is the order or sequence of bytes of a word of digital data in computer memory. Endianness is primarily expressed as big-endian (BE) or little-endian (LE). A big-endian system stores the most significant byte of a word at the smallest memory address and the least significant byte at the largest. A little-endian system, in contrast, stores the least-significant byte at the smallest address.
Double-precision floating-point format is a computer number format, usually occupying 64 bits in computer memory; it represents a wide dynamic range of numeric values by using a floating radix point.
Maple is a symbolic and numeric computing environment as well as a multi-paradigm programming language. It covers several areas of technical computing, such as symbolic mathematics, numerical analysis, data processing, visualization, and others. A toolbox, MapleSim, adds functionality for multidomain physical modeling and code generation.
IDL, short for Interactive Data Language, is a programming language used for data analysis. It is popular in particular areas of science, such as astronomy, atmospheric physics and medical imaging. IDL shares a common syntax with PV-Wave and originated from the same codebase, though the languages have subsequently diverged in detail. There are also free or costless implementations, such as GNU Data Language (GDL) and Fawlty Language (FL).
LAPACK is a standard software library for numerical linear algebra. It provides routines for solving systems of linear equations and linear least squares, eigenvalue problems, and singular value decomposition. It also includes routines to implement the associated matrix factorizations such as LU, QR, Cholesky and Schur decomposition. LAPACK was originally written in FORTRAN 77, but moved to Fortran 90 in version 3.2 (2008). The routines handle both real and complex matrices in both single and double precision.
The GNU Scientific Library is a software library for numerical computations in applied mathematics and science. The GSL is written in C; wrappers are available for other programming languages. The GSL is part of the GNU Project and is distributed under the GNU General Public License.
Computational science, also known as scientific computing or scientific computation (SC), is a rapidly growing field that uses advanced computing capabilities to understand and solve complex problems. It is an area of science which spans many disciplines, but at its core, it involves the development of models and simulations to understand natural systems.
Computational science and engineering (CSE) is a relatively new discipline that deals with the development and application of computational models and simulations, often coupled with high-performance computing, to solve complex physical problems arising in engineering analysis and design as well as natural phenomena. CSE has been described as the "third mode of discovery".
PLY is a computer file format known as the Polygon File Format or the Stanford Triangle Format. It was principally designed to store three-dimensional data from 3D scanners. The data storage format supports a relatively simple description of a single object as a list of nominally flat polygons. A variety of properties can be stored, including: color and transparency, surface normals, texture coordinates and data confidence values. The format permits one to have different properties for the front and back of a polygon. There are two versions of the file format, one in ASCII, the other in binary.
CGNS stands for CFD General Notation System. It is a general, portable, and extensible standard for the storage and retrieval of CFD analysis data. It consists of a collection of conventions, and free and open software implementing those conventions. It is self-descriptive, cross-platform also termed platform or machine independent, documented, and administered by an international steering committee. It is also an American Institute of Aeronautics and Astronautics (AIAA) recommended practice. The CGNS project originated in 1994 as a joint effort between Boeing and NASA, and has since grown to include many other contributing organizations worldwide. In 1999, control of CGNS was completely transferred to a public forum known as the CGNS Steering Committee. This Committee is made up of international representatives from government and private industry.
NetCDF is a set of software libraries and self-describing, machine-independent data formats that support the creation, access, and sharing of array-oriented scientific data. The project homepage is hosted by the Unidata program at the University Corporation for Atmospheric Research (UCAR). They are also the chief source of netCDF software, standards development, updates, etc. The format is an open standard. NetCDF Classic and 64-bit Offset Format are an international standard of the Open Geospatial Consortium.
In computing, quadruple precision is a binary floating point–based computer number format that occupies 16 bytes with precision at least twice the 53-bit double precision.
Gerris is computer software in the field of computational fluid dynamics (CFD). Gerris was released as free and open-source software, subject to the requirements of the GNU General Public License (GPL), version 2 or any later.
This glossary of computer science is a list of definitions of terms and concepts used in computer science, its sub-disciplines, and related fields, including terms relevant to software, data science, and computer programming.
WindStation is a wind energy software which uses computational fluid dynamics (CFD) to conduct wind resource assessments in complex terrain. The physical background and its numerical implementation are described in. and the official manual of the software.
Wikimedia Commons has media related to EAS3 . |