ROOT - A C++ Framework for Petabyte Data Storage, Statistical Analysis and Visualization

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, ROOT offers packages for complex data modeling and fitting, as well as multivariate classification based on machine learning techniques. 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

Slisp: A Flexible Software Toolkit for Hybrid, Embedded and Distributed Applications

We describe Slisp (pronounced ‘Ess-Lisp’), a hybrid Lisp–C programming toolkit for the development of scriptable and distributed applications. Computationally expensive operations implemented as separate C-coded modules are selectively compiled into a small Xlisp interpreter, then called as Lisp functions in a Lisp-coded program. The resulting hybrid program may run in several modes: as a stand-alone executable, embedded in a different C program, as a networked server accessed from another Slisp client, or as a networked server accessed from a C-coded client. Five years of experience with Slisp, as well experience with other scripting languages such as Tcl and Perl, are summarized. These experiences suggest that Slisp will be most useful for mid-sized applications in which the kinds of scripting and embeddability features provided by Tcl and Perl can be extended in an efficient manner to larger applications, while maintaining a well-defined standard (Common Lisp) for these extensions. In addition, the generality of Lisp makes Lisp a good candidate for an application-level communication language in distributed environments

Improving Usability of Interactive Graphics Specification and Implementation with Picking Views and Inverse Transformations

Specifying and programming graphical interactions are difficult tasks, notably because designers have difficulties to express the dynamics of the interaction. This paper shows how the MDPC architecture improves the usability of the specification and the implementation of graphical interaction. The architecture is based on the use of picking views and inverse transforms from the graphics to the data. With three examples of graphical interaction, we show how to express them with the architecture, how to implement them, and how this improves programming usability. Moreover, we show that it enables implementing graphical interaction without a scene graph. This kind of code prevents from errors due to cache consistency management

Visualisation and Grid applications of electromagnetic scattering from aircraft

Proceedings of the 2003 UK e-Science All Hands Meeting, 31st August - 3rd September, Nottingham UKElectromagnetic scattering behaviour plays a central role in the design of aircraft and other complex structures. This paper describes progress on visualisation tools in this area and on initial development of a web portal to enable scientists at remote locations to collaborate

GEANT4 : a simulation toolkit

Abstract Geant4 is a toolkit for simulating the passage of particles through matter. It includes a complete range of functionality including tracking, geometry, physics models and hits. The physics processes offered cover a comprehensive range, including electromagnetic, hadronic and optical processes, a large set of long-lived particles, materials and elements, over a wide energy range starting, in some cases, from 250 eV and extending in others to the TeV energy range. It has been designed and constructed to expose the physics models utilised, to handle complex geometries, and to enable its easy adaptation for optimal use in different sets of applications. The toolkit is the result of a worldwide collaboration of physicists and software engineers. It has been created exploiting software engineering and object-oriented technology and implemented in the C++ programming language. It has been used in applications in particle physics, nuclear physics, accelerator design, space engineering and medical physics. PACS: 07.05.Tp; 13; 2

Juice: An SVG Rendering Peer for Java Swing

SVG—a W3C XML standard—is a relatively new language for describing low-level vector drawings. Due to its cross-platform capabilities and support for events, SVG may potentially be used in interactive GUIs/graphical front-ends. However, a complete and full-featured widget set for SVG does not exist at the time of this writing. I have researched and implemented a framework which retargets a complete and mature raster- based widget library—the JFC Swing GUI library—into a vector-based display substrate: SVG. My framework provides SVG with a full-featured widget set, as well as augmenting Swing’s platform coverage. Furthermore, by using bytecode instrumentation techniques, my Swing to SVG bridging framework is transparent to the developers— allowing them to implement their user interfaces in pure Swing