Miguel C ASQUILHO CERENA “Centre for Natural Resources and the Environment” (CPQ) Department of...

Miguel CASQUILHOMiguel CASQUILHOCERENA “Centre for Natural Resources and the Environment” (CPQ)Department of Chemical Engineering

Marco CUNHAMarco CUNHADept. of Computer Science and Engineering

IST Instituto Superior TécnicoUL Universidade de Lisboa

(University of Lisbon)

http://web.tecnico.ulisboa.pt/http://web.tecnico.ulisboa.pt/mcasquilho/mcasquilho/

Scientific computing over the WebScientific computing over the Webin in various programming languagesvarious programming languages

21-Jun-2014 Scientific computing over the Web 1 / 15

21-Jun-2014 Scientific computing over the Web

solving problems in Fortran, C, and Octavesolving problems in Fortran, C, and OctaveABSTRACT    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:•Scientific computing: two illustrative problems•Solving problems in Fortran, C, and Octave•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 WebScientific computing over the Webin in various programming languages:various programming languages:

21-Jun-2014 Scientific 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 WebScientific computing over the Webin in various programming languagesvarious programming languages

21-Jun-2014 Scientific computing over the Web 4 / 15

1. 2. 3. Scientific computing: two illustrative problems

PROBLEM 1) Suppose the following relation:

or simply

Let, e.g., n = 106:

This reminds of ! For n , does x tend to ?! More generally, does this

tend to the following ? CONJECTURE

nnn xxx

11

21,1414x

x

axx :

xxx

1:

1,4142132 nxn 2

naxn 2

21-Jun-2014 Scientific computing over the Web 5 / 15

1. 2. 3. Scientific computing: two illustrative problems

PROBLEM 1) Graphically (n = 106), e.g. with a = 4,5: x0 = 1 (Very) fast convergence

x0 = 500 Slower

convergence

Conjecture: confirmed ?

21-Jun-2014 Scientific computing over the Web 6 / 15

1. 2. 3. Scientific computing: two illustrative problems

PROBLEM 2) What is the distribution of the distance from a given point () to the random points in a circle (R = 1) ?

E.g., for x0 = 0,6:

21-Jun-2014 Scientific computing over the Web 7 / 15

1. 2. 3. Scientific computing: two illustrative problems

PROBLEM 2) Is there an analytical expression for these curves ? We used Monte Carlo simulation.

Curves for x0 = 2,2; 0,2; 00. Anyway, for 00: y = 2 x (!)

21-Jun-2014 Scientific 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 composerMadrid

8 / 15

Scientific computing over the WebScientific computing over the Webin in various programming languagesvarious programming languages

21-Jun-2014 Scientific computing over the Web

1. 2. 3. Solving problems in Fortran, C, and Octave

9 / 15

Problem 1)Problem 1) Problem 2)Problem 2) Writing the code

• Fortran, C: ~3 h; Octave: ~20 min Executing

• Fortran, C: ~5 ms 250 ms• Octave: ~70 s 115 s

xaxx :

Link

1. Scientific computing: two illustrative problems

2. Solving problems in Fortran, C, and Octave

3. Conclusions

21-Jun-2014 Scientific computing over the Web

Henrique Medina(1901–1988)

Salvador Dalí(1904-1989)

10 / 15

Scientific computing over the WebScientific computing over the Webin in various programming languagesvarious programming languages

21-Jun-2014 Scientific 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

21-Jun-2014 Scientific 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

21-Jun-2014 Scientific 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

21-Jun-2014 Scientific 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)

• 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)

• 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)

Bibliography

14 / 15

Miguel CASQUILHOMiguel CASQUILHOCERENA “Centre for Natural Resources and the Environment” (CPQ)Department of Chemical Engineering

Marco CUNHAMarco CUNHADept. of Computer Science and Engineering

IST Instituto Superior TécnicoUL Universidade de Lisboa

(University of Lisbon)

http://web.tecnico.ulisboa.pt/http://web.tecnico.ulisboa.pt/mcasquilho/mcasquilho/

Scientific computing over the WebScientific computing over the Webin in various programming languagesvarious programming languages

21-Jun-2014 Scientific computing over the Web 15 / 15