1. 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

2. 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:

3. 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

4. 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

5. 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 ?

6. 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:

7. 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 (!)

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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