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Miguel C ASQUILHO CERENA “Centre for Natural Resources and the Environment” (CPQ) Department of Chemical Engineering Marco C UNHA Dept. of Computer Science and Engineering IST Instituto Superior Técnico UL Universidade de Lisboa (University of Lisbon) http://web.tecnico.ulisboa.pt/mcasquilho/ Scientific computing over the Web in various programming languages 21-Jun-2014Scientific computing over the Web1 / 15

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21-Jun-2014Scientific computing over the Web solving problems in Fortran, C, and Octave A BSTRACT Scientific computing over the Web (no installations) is shown with classical (Fortran 90, C) and modern (Octave) languages, to solve two numerical problems (having surprising results): a certain simple series, and the distance to random points in a circle. Our objective is twofold: (i) to emphasize the pertinence of the Web for scientific computing, and (ii) to comment the productiveness of the modern languages. The following points are addressed: 1.Scientific computing: two illustrative problems 2.Solving problems in Fortran, C, and Octave 3.Conclusions From the authors’ experience, the Web environment is recommended for scientific computing for: academic and industrial purposes, and the academy-industry connection. 2 / 15 Scientific computing over the Web in various programming languages:

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21-Jun-2014Scientific computing over the Web 1.Scientific computing: two illustrative problems 2.Solving problems in Fortran, C, and Octave 3.Conclusions Ernesto Halffter (1905–1989) Lisboa 1938–1954 3 / 15 Scientific computing over the Web in various programming languages

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21-Jun-2014Scientific computing over the Web4 / 15 1. 2. 3. Scientific computing: two illustrative problems P ROBLEM 1) Suppose the following relation: or simply Let, e.g., n = 10 6 : This reminds of ! For n , does x tend to ?! More generally, does this tend to the following ? CONJECTURE

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21-Jun-2014Scientific computing over the Web5 / 15 1. 2. 3. Scientific computing: two illustrative problems P ROBLEM 1) Graphically (n = 10 6 ), e.g. with a = 4,5: x 0 = 1 (Very) fast convergence x 0 = 500 Slower convergence Conjecture: confirmed ?

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21-Jun-2014Scientific computing over the Web6 / 15 1. 2. 3. Scientific computing: two illustrative problems P ROBLEM 2) What is the distribution of the distance from a given point ( ) to the random points in a circle (R = 1) ? E.g., for x 0 = 0,6:

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21-Jun-2014Scientific computing over the Web7 / 15 1. 2. 3. Scientific computing: two illustrative problems P ROBLEM 2) Is there an analytical expression for these curves ? We used Monte Carlo simulation. 00 Curves for x 0 = 2,2; 0,2; 0. Anyway, for 0: y = 2 x (!)

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21-Jun-2014Scientific computing over the Web 1.Scientific computing: two illustrative problems 2.Solving problems in Fortran, C, and Octave 3.Conclusions Alexandre Rey Colaço (1854-1928) Portuguese composer Madrid 8 / 15 Scientific computing over the Web in various programming languages

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21-Jun-2014Scientific computing over the Web 1. 2. 3. Solving problems in Fortran, C, and Octave 9 / 15 Problem 1)Problem 2) Writing the code Fortran, C: ~3 h; Octave: ~20 min Executing Fortran, C: ~5 ms250 ms Octave: ~70 s115 s Link

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1.Scientific computing: two illustrative problems 2.Solving problems in Fortran, C, and Octave 3.Conclusions 21-Jun-2014Scientific computing over the Web Henrique Medina (1901–1988) Salvador Dalí (1904-1989) 10 / 15 Scientific computing over the Web in various programming languages

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21-Jun-2014Scientific computing over the Web Scientific computing over the Web has (we think) lagged behind most other aspects in the Web. Making “scientific” (or industrial, etc.) applications accessible over the Web: avoids platform incompatibilities (Windows, Mac, Linux, etc.); and dispenses with any software installation (facilitating work in the classroom and in various enterprise tasks). For many problems such as the ones shown: the “old” (laborious) languages (Fortran, C) work well, indifferently, over the Web or not; and the “new” (productive) languages (Matlab) show various obstacles (licence !, time) --- hence, Octave. 1. 2. 3. Conclusions (1 of 2) 11 / 15

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21-Jun-2014Scientific computing over the Web So, we use and recommend scientific computing over the Web for academic or industrial purposes. For scientific computing over the Web, only the framework is difficult to implement. Further applications can be trivial. So, your problems are welcome ! 1. 2. 3. Conclusions (2 of 2) 12 / 15

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21-Jun-2014Scientific computing over the Web DEQ, DEI: Department of Chemical Engineering, and Department of Computer Science and Engineering — IST, University of Lisbon CERENA (CPQ): Centre for Natural Resources and the Environment (Centre for Chemical Processes), IST (Ulisboa) CIIST: “Centro de Informática do IST” (Centre for Informatics), IST, ULisboa Milipeia, Lab. de Computação Avançada (Lab. of Advanced Computing), University of Coimbra Prof. Jorge Buescu, Dept. of Mathematics, Faculty of Sciences, ULisboa Keywords Scientific computing, Internet, computer languages Acknowledgements 13 / 15

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21-Jun-2014Scientific computing over the Web Casquilho, M. [2012] “Scientific computing on the Internet, a little-trodden field”, Universidade Aberta, Porto Salvo. Casquilho, M. [2013] “Computação científica, Internet, Indústria” (Scientific computing, Internet, Industry), 1.st Portuguese Meeting on Mathematics for Industry, FCUP, Universidade do Porto, Porto, 06–08 June. Ferreira, Miguel, Miguel Casquilho [2013] "A web application for distributed computing — solving a typical statistical problem in industry", CISTI'2013, 8.ª Conf. Ibérica de Sistemas e Tecnologias de Informação (8.th Iberian Conf. on Information Systems and Technologies), Lisbon (Portugal)CISTI'2013 Ferreira, M., M. Casquilho [2013] “Scientific computing over the Internet: an example in Geometry”, WorldCIST'13, World Conference on Information Systems and Technologies, Olhão (Portugal)WorldCIST'13 Franco, B., M. Casquilho [2011] “A Web application for scientific computing: combining several tools and languages to solve a statistical problem”, CISTI'2011, 6.ª Conferência Ibérica de Sistemas e Tecnologias de Informação, Chaves (Portugal) CISTI'2011 Bibliography 14 / 15

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Miguel C ASQUILHO CERENA “Centre for Natural Resources and the Environment” (CPQ) Department of Chemical Engineering Marco C UNHA Dept. of Computer Science and Engineering IST Instituto Superior Técnico UL Universidade de Lisboa (University of Lisbon) http://web.tecnico.ulisboa.pt/mcasquilho/ Scientific computing over the Web in various programming languages 21-Jun-2014Scientific computing over the Web15 / 15

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