Re: [Scilab-users] inquiry
Hello, De la part de Mohammed Bashir Envoyé : mardi 18 février 2014 00:34 is scilab equivalent to matlab You might have a look at Alan Edelman, Open Source and Traditional Technical Computing, MIT (2010) https://www.scilab.org/content/download/395/2850/file/ScilabTec_Keynote.pdf Best regards -- Christophe Dang Ngoc Chan Mechanical calculation engineer __ This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error), please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden. __ ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
[Scilab-users] evaluate error on each parameter calculated with leastsq
Hi all !! First of all, thank you to all contributors of Scilab. However, I have a problem to calculate the estimated error on each parameter calculated with leastsq. For example if I have the simple following function to fit: !!! function y = fun2fit(x, c) y = c(1)*x*x + c(2)*x + c(3); endfunction function e = myerror(c, x, y) e = fun2fit(x, c) - y; endfunction // Data x = [ 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6]'; y = [5.02 6.08 3.33 -0.93 -0.22 7.83 16.52 15.55 2.67 -11.42 -11.78 5.09 25.25]'; // First guess c0 = [1 1 1]'; y0 = fun2fit(x, c0); // least square [f, copt] = leastsq(list(myerror, x, y), c0) !!! I'd like to have an estimated error on each of the 3 element of copt. Any idea ? Thanks ! Y -- View this message in context: http://mailinglists.scilab.org/evaluate-error-on-each-parameter-calculated-with-leastsq-tp4028696.html Sent from the Scilab users - Mailing Lists Archives mailing list archive at Nabble.com. ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
[Scilab-users] Installation of SIVP fo Scilab
I can't execute the builder file of SIVP because this module need a
compileur
--exec('builder.sce')
--mode(-1);
Création des macros...
-- Création de [SIVPlib] (Macros) --
!--error 1
tbx_builder_gateway : Ce module requiert un compilateur C mais celui-ci n'a
pas pu être trouvé.
at line 27 of function tbx_builder_gateway called by :
tbx_builder_gateway(toolbox_dir);
at line 35 of exec file called by :
exec('builder.sce')
* on the read file it is written that we need a version of scilab older than
the 2.0 version but there are not avalaible anymore, maybe this could pose a
problem ?
* i have installed Eclipse (with mingw) for the occasion, maybe i can create
a link between Eclipse and Scilabe to solve the problem ?
* I also installed OPEN CV but i don't know what i have to do with it ? it
put itself automatically in the PATH but that's all for SIVP use ?
Thank you for your answer,
Sorry for my english,
Ronan SY
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Re: [Scilab-users] Rounding error or precision setting?
Hi The function *clean *does that: clean(cos(%pi)+%i*sin(%pi)) Note that the limited precision of floating point numbers is a general issue in computer science. http://en.wikipedia.org/wiki/Floating_point#Representable_numbers.2C_conversion_and_rounding You should be aware of that for instance when testing numbers, as in: if cos(%pi)+%i*sin(%pi) == -1 disp(i am a mathematician) else disp(i am a computer) end if abs(cos(%pi)+%i*sin(%pi) +1)1d-8 disp(yep) else disp(nope) end or when you calculate indefinite integrals. Also note that some modules on ATOMS and scilabfilexchange allow to make computation with arbitrary (but not infenitesimal) precision. On 19/02/2014 15:15, Lester Anderson wrote: Hello, Just a quick query. Not been using Scilab for a while, so maybe I have missed something, but is there a built-in precision setting for working with real and imaginary functions? Tried the Euler formula (special case) in Scilab 5.4.1: --x=cos(%pi)+(%i*sin(%pi)) x = - 1. + 1.225D-16i --y=%e^(%i*%pi) y = - 1. + 1.225D-16i The real part is fine, but the complex has a measured value (approaching zero). Is there a way to tell Scilab if this gets beyond a limit to round off at zero say? Sure this is an easy one! Cheers Lester ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users -- Adrien Vogt-Schilb PhD Student (Cired) ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
Re: [Scilab-users] Rounding error or precision setting?
Hello, De la part de Lester Anderson Envoyé : mercredi 19 février 2014 15:16 Is there a way to tell Scilab if this gets beyond a limit to round off at zero say? Maybe format() or clean() ? http://help.scilab.org/docs/5.4.1/en_US/format.html http://help.scilab.org/docs/5.4.1/en_US/clean.html Best regards -- Christophe Dang Ngoc Chan Mechanical calculation engineer __ This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error), please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden. __ ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
Re: [Scilab-users] Rounding error or precision setting?
Thanks for the pointer - knew it was a simple one! Cheers On 19 February 2014 14:25, Dang, Christophe christophe.d...@sidel.comwrote: Hello, De la part de Lester Anderson Envoyé : mercredi 19 février 2014 15:16 Is there a way to tell Scilab if this gets beyond a limit to round off at zero say? Maybe format() or clean() ? http://help.scilab.org/docs/5.4.1/en_US/format.html http://help.scilab.org/docs/5.4.1/en_US/clean.html Best regards -- Christophe Dang Ngoc Chan Mechanical calculation engineer __ This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error), please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden. __ ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
Re: [Scilab-users] evaluate error on each parameter calculated with leastsq
Dear Yohann The (x,y) dataset does not look like a parabola... (it resembles more a type of x*sin(x) function). Trying to fit this dataset with a parabola, will not only give unreliable result, but also will put a high challenge to error estimation algorithms... Denis -Message d'origine- De : users [mailto:users-boun...@lists.scilab.org] De la part de Yohann Envoyé : mardi 18 février 2014 15:07 À : users@lists.scilab.org Objet : [Scilab-users] evaluate error on each parameter calculated with leastsq Hi all !! First of all, thank you to all contributors of Scilab. However, I have a problem to calculate the estimated error on each parameter calculated with leastsq. For example if I have the simple following function to fit: !!! function y = fun2fit(x, c) y = c(1)*x*x + c(2)*x + c(3); endfunction function e = myerror(c, x, y) e = fun2fit(x, c) - y; endfunction // Data x = [ 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6]'; y = [5.02 6.08 3.33 -0.93 -0.22 7.83 16.52 15.55 2.67 -11.42 -11.78 5.09 25.25]'; // First guess c0 = [1 1 1]'; y0 = fun2fit(x, c0); // least square [f, copt] = leastsq(list(myerror, x, y), c0) !!! I'd like to have an estimated error on each of the 3 element of copt. Any idea ? Thanks ! Y -- View this message in context: http://mailinglists.scilab.org/evaluate-error-on-each-parameter-calculated-with-leastsq-tp4028696.html Sent from the Scilab users - Mailing Lists Archives mailing list archive at Nabble.com. ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
Re: [Scilab-users] evaluate error on each parameter calculated with leastsq
Hi Yohan I see that I'm not alone wondering a bit about what you'd like to do. A mathematically solid and readily available technique to corner mathematical rounding errors and other errors of operation is called Interval Analysis. For matlab there's INTLAB. See: http://www.ti3.tu-harburg.de/~rump/intlab/ I'm sure it could be converted to Scilab without big trouble. Maybe I even have an old one laying around (??) somewhere ... maybe. Another approach would be in a specific situation to apply the techniques of interval analysis, only centered around your concern ... and leave the rest of your script normal. Best regards, Claus On 2/18/2014 15:06, Yohann wrote: Hi all !! First of all, thank you to all contributors of Scilab. However, I have a problem to calculate the estimated error on each parameter calculated with leastsq. For example if I have the simple following function to fit: !!! function y = fun2fit(x, c) y = c(1)*x*x + c(2)*x + c(3); endfunction function e = myerror(c, x, y) e = fun2fit(x, c) - y; endfunction // Data x = [ 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6]'; y = [5.02 6.08 3.33 -0.93 -0.22 7.83 16.52 15.55 2.67 -11.42 -11.78 5.09 25.25]'; // First guess c0 = [1 1 1]'; y0 = fun2fit(x, c0); // least square [f, copt] = leastsq(list(myerror, x, y), c0) !!! I'd like to have an estimated error on each of the 3 element of copt. Any idea ? Thanks ! Y -- View this message in context: http://mailinglists.scilab.org/evaluate-error-on-each-parameter-calculated-with-leastsq-tp4028696.html Sent from the Scilab users - Mailing Lists Archives mailing list archive at Nabble.com. ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users . --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
[Scilab-users] To find maximum value in a random curve
Hi all, I have a random 2D-curve which is defined by a set of points (I don't know the equation of the curve), obtained by interpolation. How can I find the maximum, minimum, inflexion points on this curve. Thank you very much! -- View this message in context: http://mailinglists.scilab.org/To-find-maximum-value-in-a-random-curve-tp4028741.html Sent from the Scilab users - Mailing Lists Archives mailing list archive at Nabble.com. ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
Re: [Scilab-users] evaluate error on each parameter calculated with leastsq
Hi Antoine, thank you for your answer but what I need is a confidence interval on each parameter ! Cheers Yohann -- View this message in context: http://mailinglists.scilab.org/evaluate-error-on-each-parameter-calculated-with-leastsq-tp4028696p4028742.html Sent from the Scilab users - Mailing Lists Archives mailing list archive at Nabble.com. ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
