A. Kreshuk

CERN, Genève, Geneva, Switzerland

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Publications (4)2.41 Total impact

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    ABSTRACT: ROOT is an object-oriented C++ framework conceived in the high-energy physics (HEP) community, designed for storing and analyzing petabytes of data in an efficient way. Any instance of a C++ class can be stored into a ROOT file in a machine-independent compressed binary format. In ROOT the TTree object container is optimized for statistical data analysis over very large data sets by using vertical data storage techniques. These containers can span a large number of files on local disks, the web, or a number of different shared file systems. In order to analyze this data, the user can chose out of a wide set of mathematical and statistical functions, including linear algebra classes, numerical algorithms such as integration and minimization, and various methods for performing regression analysis (fitting). In particular, the RooFit package allows the user to perform complex data modeling and fitting while the RooStats library provides abstractions and implementations for advanced statistical tools. Multivariate classification methods based on machine learning techniques are available via the TMVA package. A central piece in these analysis tools are the histogram classes which provide binning of one- and multi-dimensional data. Results can be saved in high-quality graphical formats like Postscript and PDF or in bitmap formats like JPG or GIF. The result can also be stored into ROOT macros that allow a full recreation and rework of the graphics. Users typically create their analysis macros step by step, making use of the interactive C++ interpreter CINT, while running over small data samples. Once the development is finished, they can run these macros at full compiled speed over large data sets, using on-the-fly compilation, or by creating a stand-alone batch program. Finally, if processing farms are available, the user can reduce the execution time of intrinsically parallel tasks — e.g. data mining in HEP — by using PROOF, which will take care of optimally distributing the work over the available resources in a transparent way.Program summaryProgram title: ROOTCatalogue identifier: AEFA_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFA_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: LGPLNo. of lines in distributed program, including test data, etc.: 3 044 581No. of bytes in distributed program, including test data, etc.: 36 325 133Distribution format: tar.gzProgramming language: C++Computer: Intel i386, Intel x86-64, Motorola PPC, Sun Sparc, HP PA-RISCOperating system: GNU/Linux, Windows XP/Vista, Mac OS X, FreeBSD, OpenBSD, Solaris, HP-UX, AIXHas the code been vectorized or parallelized?: YesRAM:>55 MbytesClassification: 4, 9, 11.9, 14Nature of problem: Storage, analysis and visualization of scientific dataSolution method: Object store, wide range of analysis algorithms and visualization methodsAdditional comments: For an up-to-date author list see: http://root.cern.ch/drupal/content/root-development-team and http://root.cern.ch/drupal/content/former-root-developersRunning time: Depending on the data size and complexity of analysis algorithmsReferences:[1]http://root.cern.ch.
    Computer Physics Communications 06/2011; 180(12-180):2499-2512. DOI:10.1016/j.cpc.2009.08.005 · 2.41 Impact Factor
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    ABSTRACT: For the last several months the main focus of development in the ROOT I/O package has been code consolidation and performance improvements. We introduced a new pre-fetch mechanism to minimize the number of transactions between client and server, hence reducing the effect of latency on the time it takes to read a file both locally and over wide are network. We will review the implementation and how well it works in different conditions (gain of an order of magnitude for remote file access). We will also briefly describe new utilities, including a faster implementation of TTree cloning (gain of an order of magnitude), a generic mechanism for object references, and a new entry list mechanism tuned both for small and large number of selections. In addition to reducing the coupling with the core module and becoming its owns library (libRIO) (as part of the general restructuring of the ROOT libraries), the I/O package has been enhanced in the area of XML and SQL support, thread safety, schema evolution, tree queries, and many other areas.
    Journal of Physics Conference Series 07/2008; 119(4):042006. DOI:10.1088/1742-6596/119/4/042006
  • R. Brun, A. Kreshuk, L. Moneta