FREE/OPEN SOURCE SOFTWARE: an ALTERNATIVE for ENGINEERING STUDENTS Paulo S
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Session T3G FREE/OPEN SOURCE SOFTWARE: AN ALTERNATIVE FOR ENGINEERING STUDENTS Paulo S. Motta Pires1, David A. Rogers2 Abstract ¾ Networked or stand-alone computational · Next, the Linux operating system is introduced. environments that are available as free or open-source Options for installation on different computing systems software are very useful for teaching engineering courses. are outlined along with some of its distinctive The cost of implementation of these environments is characteristics. essentially that of the underlying personal computer (PC) · Finally, the Scilab software package is presented. hardware. The necessary software, of very high quality, is available free of charge through the Internet. Our purpose is The main body of this paper contains the following to show that free or open source software can be used as a elements: (1) a brief description of the main software good alternative for engineering students. The main focus is packages used is given, (2) a survey of some Scilab on Scilab, a numerical software package. Often installed characteristics and capabilities (includes an overview of on machines running the Linux operating system, it is a commands and functions) that are appropriate for powerful tool that is useful in teaching numerical methods or engineering students is presented, and (3) examples of computationally intensive disciplines. Also presented are Scilab utilization in numerical methods courses for other free software packages, GSL (GNU Scientific Library) undergraduates and suggestions for utilization in graduate and LaTeX, that can be useful to the student. A package like courses are given. For economy of space, the second and Scilab can serve the needs of students when standard third elements are combined. Finally, some suggestions for commercial mathematical software is not available. including other useful material in these courses will be presented. The procedures used to install the necessary Index Terms—Free/open source software, numerical software are outlined in the Appendix. methods, programming language, Scilab. DESCRIPTION OF THE SOFTWARE PACKAGES INTRODUCTION The Linux operating system is a free, open-source multi-task There is no doubt that the Internet has changed engineering and multi-user operating system that is well known and education, especially in providing rapid and, often, free widely used. Linux was first developed for 32-bit Intel x86- access to information. Teachers, researchers, and students based personal computers (386 or higher) but has been can use the Internet to improve their professional knowledge ported to SUN SPARC and UltraSPARC machines, and skills. Motorola 68000-based machines, Power PCs, the IBM The Internet is also a vast and rich repository of S/390, the Intel IA-64, and others. free/open source computational software environments. There are several Linux flavors or distributions. For Very high quality packages are available for mathematics, PCs, the following are examples of such distributions: numerical analysis, parallel computing, data processing, RedHat [5], Suse [6], Mandrake [7], Slackware [8], Debian image visualization, graphics, text preparation and [9] and Conectiva [10]. The latter is a distribution that is presentation, and so on [1]. In this paper the central focus available to Portuguese- and Spanish-speaking users. Linux will be Scilab [2]-[3], often used in combination with Linux can be downloaded through the Internet. The choice would [4]. These alternatives give the student or professional with be the ISO (ISO9660 type) files that are about 600 MB in limited resources a long-term capability for performing size. With the ISO file the user burns an installation CD for significant computational studies. himself or herself. If the Internet connection is slow, one The approach used in this work is to introduce free/open can purchase Linux on CDs from several vendors including source software in numerically intensive graduate and local bookstores. Installation instructions come with the undergraduate courses as described below: distribution files or from the Linux HOWTO guides [11]. · First, the free/open source software philosophy is These guides are translated into several languages and are presented. Emphasis is placed on World Wide Web available in several file formats. search mechanisms and the opportunity that the students Scilab, a numerical software package developed at have to access information that will permit them to do INRIA (Institut National de Recherche en Informatique et en their jobs better. Automatique), France, is similar in some respects to MATLABâ [12]. It uses an interactive graphical 1 Paulo S. Motta Pires, Depto. de Engenharia de Computação e Automação, Univ. Federal do Rio Grande do Norte (UFRN), Brazil, [email protected] 2 David A. Rogers, Dept. of Electrical and Computer Engineering, North Dakota State University, Fargo, ND, 58105, [email protected] 0-7803-7444-4/02/$17.00 © 2002 IEEE November 6 - 9, 2002, Boston, MA 32nd ASEE/IEEE Frontiers in Education Conference T3G-7 Session T3G environment combined with a higher level programming examples of these data types are given. To illustrate, the language. The Scilab language can be interfaced easily with polynomial C or FORTRAN programs using dynamic links, through the 1+ 2s link primitive, or using interfacing or gateway programs. with coefficients 1 and 2 and variable s, can be defined using The latter programs can be written by the user following the the command poly, examples distributed with the Scilab package or generated -->poly([1 2], ‘s’, ‘c’). through the Scilab Intersi companion toolbox. Also, Scilab The Scilab prompt is the “-->” sign. A row vector can be can be used to do symbolic computation through an interface defined using with Maple software [13]. Several high quality toolboxes are -->w = [1 2 3]. available to Scilab users, such as: Scicos, a package for To define a row vector, the elements should be separated by modeling and simulation of dynamical systems; ANN, the blanks or by commas. To define a column vector, the Artificial Neural Network toolbox; the Signal Processing elements should be separated by a semicolon as in [1; 2; 3]. toolbox; and FRACLAB (Fractal, Multifractal and Wavelet The handling of input and output of vector and matrix files Analysis toolbox). Scilab also has an extension called follows. For example, the elements of the matrix A, Parallel Scilab, Scilab // [14]-[15], that supports the execution of parallel jobs within Scilab. This extension can é1 2 3 4ù ê ú run on parallel machines or on a network of workstations A = 5 6 7 8 (NOWs) and is based on the Parallel Virtual Machine, PVM, ê ú software paradigm [16]. Scilab has introductory ëê9 2 3 4ûú documentation in several languages (English, French, can be stored in an ASCII file called matrixA and read to Spanish, and Portuguese). the Scilab environment using the command read, -->A = read(‘matrixA’, 3, 4). SCILAB FOR ENGINEERING STUDENTS In this case, the numbers contained in the archive matrixA will be assigned to the variable A. Finally, loops (for and Engineering students at both the undergraduate and graduate while), conditional commands (if-then-else, select-case), levels will normally need an introduction to the graphics the concept of local and global variables, and the structure environment of the software. Scilab can also run in Linux of functions are presented. At each point the student does text mode if it is started as “scilab -nw”, but that will not be some hands-on exercises considered here. Scilab’s menu structure and its built-in The process of introducing students to Scilab culminates libraries are typical initial elements to be presented in a with Scilab seen as a programming development course. Some representative built-in Scilab libraries that environment. The students develop programs as separate would be of interest in most classes are listed below: files, load these files into the Scilab environment, and · Scilab programming. Consists of several commands execute their code. Here Scilab is used as a programming and functions that can be used to program with Scilab. environment to operate in some of the following areas: · Graphics functions, the functions to draw 2D and 3D · Non-linear equation solving using the bisection and graphics. Newton-Raphson methods · Elementary mathematical functions. · Direct methods for solving linear equation systems · Input/output functions. (Gauss triangularization, LU decomposition) · Linear algebra functions. · Iterative methods for solving linear equation systems (Gauss-Jacobi and Gauss-Siedel methods) In the sections that follow, the use of Scilab in · Numerical solutions of non-linear systems of equations undergraduate and graduate courses will be considered (Newton methods) separately. · Initial-value problems for ordinary differential SCILAB FOR UNDERGRADUATES equations (Runge-Kutta methods) · Numerical integration (Simpson and Romberg methods) Scilab can be introduced to students initially as a very · Interpolation and polynomial approximation powerful calculator. At this level, students are exposed to promp t-line operations. They learn to edit command lines, Figure 1 shows a typical program example written in the how to use comments, and how to manipulate files and Scilab programming language that is appropriate for an directories in the Scilab environment. Several basic undergraduate numerical methods course. This program is operations are performed with real and complex numbers used to solve the ordinary differential equation, and with several elementary mathematical functions. The dy objective at this point is to acquaint the students with the = (x - y)/ 2 (1) environment. Next, students become familiar with dx polynomials, vectors, matrices, and lists data types. Several in the interval [a,b] with step h using the traditional fourth order Runge-Kutta numerical integration method defined by: 0-7803-7444-4/02/$17.00 © 2002 IEEE November 6 - 9, 2002, Boston, MA 32nd ASEE/IEEE Frontiers in Education Conference T3G-8 Session T3G h arguments and the parameter XY is the output argument. yk+1 = yk + ( f1 + 2 f2 + 2 f 3 + f 4 ).