Re: [Scilab-users] inquiry
Hi Mohammed, Scilab and Matlab are meant for the same purposes and share many similar features, but their semantic, function names and conventions are not exactly the same. So no, they are not directly equivalent, but a Scilab job is often translatable in Matlab, and vice versa. Check out the Matlab-Scilab equivalents http://help.scilab.org/docs/5.4.1/fr_FR/section_36184e52ee88ad558380be4e92d3de21.html http://help.scilab.org/docs/5.4.1/fr_FR/section_36184e52ee88ad558380be4e92d3de21.htmlhelp page for more information. Regards, Paul On 02/18/2014 12:33 AM, Mohammed Bashir wrote: is scilab equivalent to matlab On Mon, Nov 25, 2013 at 3:06 PM, Mohammed Bashir mobash2...@gmail.com mailto:mobash2...@gmail.com wrote: is scilab equivalent to matlab ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users -- Paul BIGNIER Scilab Engineer Xcos Developer --- Scilab Enterprises 143bis rue Yves Le Coz - 78000 Versailles, France Phone: +33.1.80.77.04.69 http://www.scilab-enterprises.com ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
Re: [Scilab-users] Xcos PID controller problem
The PID controller is an improper transfer function (degree of numdegree of den). In Xcos the derivative term of the PID bloc is computed by an approximation which seems to fail in your context. A solution should be to replace the PID bloc with a transfert function block made proper adding a very small term in s^2 for the denominator (sse the attched diagram) Please report the problem in http://bugzilla.scilab.org/ Serge Steer Le 17/02/2014 21:51, john a écrit : Hello, I'm new to Scilab and Xcos so may be making a simple mistake, but I have the following problem. I created an Xcos model of a simple mass-spring-damper with PID control using the data from the Matlab example shown here http://ctms.engin.umich.edu/CTMS/index.php?example=Introductionsection=ControlPID . The Xcos results are the same as the Matlab example except for the case when all three gains are used as follows Kp=350, Ki=300 and Kd=50 . My result looks like this (red line) and is clearly giving a different response to the Matlab example for the same gain values. http://mailinglists.scilab.org/file/n4028669/PID.png I have tried different solvers and time steps, but this doesn't seem to be the problem. I have also modelled the problem in Mathcad 7, Mathcad Prime 3 and using csim in Scilab and all those results agree broadly with the Matlab example. Any advice would be greatly appreciated and I have attached the Xcos file for information. spring-damper-PID.zcos http://mailinglists.scilab.org/file/n4028669/spring-damper-PID.zcos -- View this message in context: http://mailinglists.scilab.org/Xcos-PID-controller-problem-tp4028669.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 spring-damper-PID.zcos Description: Binary data ___ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
[Scilab-users] How to get a reguar sampled vector in Scilab
I'm trying to program function (or even better it it already exists) in scilab that calculates a regular timed samples of values. IE: I have a vector 'values' which defines contains the value of a signal at different times. This times are in the vector 'times'. So at time times(N), the signal has value values(N). At the moment the times are not regular, so the variable 'times' and 'values' can look like: times = [0, 2, 6, 8, 14] values= [5, 9, 10, 1, 6] This represents that the signal had value 5 from second 0 to second 2. Value 9 from second 2 to second 6, etc. Therefore, if I want to calculate the signal average value I can not just calculate the average of vector 'values'. This is because for example the signal can be for a long time with the same value, but there will be only one value in the vector. One option is to take the deltaT to calculate the media, but I will also need to perform other calculations:average, etc. Other option is to create a function that given a deltaT, samples the time and values vectors to produce an equally spaced timeVector and corresponding values. For example, with deltaT=2 and the previous vectors, [sampledTime, sampledValues] = regularSample(times, values, 2) sampledTime = [0, 2, 4, 6, 8, 10, 12, 14] sampledValues = [5, 9, 9, 10, 1, 1, 1, 6] This is easy if deltaT is small enough to fit exactly with all the times. If the deltaT is bigger, then the average of values or some aproximation must be done... Is there anything already done in Scilab? How can this function be programmed? Thanks a lot! PS: I don't know if this is the correct forum to post scilab questions, so any pointer would also be useful. -- View this message in context: http://mailinglists.scilab.org/How-to-get-a-reguar-sampled-vector-in-Scilab-tp4028712.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] How to get a reguar sampled vector in Scilab
I think there is a little mistake in the sampledValues you are expecting: times = [0, 2, 6, 8, 14] values= [5, 9, 10, 1, 6] sampledTime = [0, 2, 4, 6, 8, 10, 12, 14] sampledValues = [5, 9, 9, 10, 1, 1, 1, 6] According to the rule used for the previous values, the last value of sampledValues must be 1 and not 6 Here is a code doing what you expect (but with a different last point) times = [0, 2, 6, 8, 14]; values= [5, 9, 10, 1, 6]; sampletimes=0:14; V=zeros(sampletimes); for k=1:size(times,'*')-1 V(sampletimes=times(k)sampletimestimes(k+1))=values(k); end V(sampletimestimes($))=timesvalues($); clf;plot(sampletimes,V,'-+') //You can also use linear interpolation V1=interpln([times;values],sampletimes); plot(sampletimes,V1,'r-+') //or Splin interpolation V2=interp(sampletimes,times,values,splin(times,values)) plot(sampletimes,V2,'m-*') Serge Steer - Mail original - De: Matiasb mati...@gmail.com À: users@lists.scilab.org Envoyé: Mardi 18 Février 2014 20:59:10 Objet: [Scilab-users] How to get a reguar sampled vector in Scilab I'm trying to program function (or even better it it already exists) in scilab that calculates a regular timed samples of values. IE: I have a vector 'values' which defines contains the value of a signal at different times. This times are in the vector 'times'. So at time times(N), the signal has value values(N). At the moment the times are not regular, so the variable 'times' and 'values' can look like: times = [0, 2, 6, 8, 14] values= [5, 9, 10, 1, 6] This represents that the signal had value 5 from second 0 to second 2. Value 9 from second 2 to second 6, etc. Therefore, if I want to calculate the signal average value I can not just calculate the average of vector 'values'. This is because for example the signal can be for a long time with the same value, but there will be only one value in the vector. One option is to take the deltaT to calculate the media, but I will also need to perform other calculations:average, etc. Other option is to create a function that given a deltaT, samples the time and values vectors to produce an equally spaced timeVector and corresponding values. For example, with deltaT=2 and the previous vectors, [sampledTime, sampledValues] = regularSample(times, values, 2) sampledTime = [0, 2, 4, 6, 8, 10, 12, 14] sampledValues = [5, 9, 9, 10, 1, 1, 1, 6] This is easy if deltaT is small enough to fit exactly with all the times. If the deltaT is bigger, then the average of values or some aproximation must be done... Is there anything already done in Scilab? How can this function be programmed? Thanks a lot! PS: I don't know if this is the correct forum to post scilab questions, so any pointer would also be useful. -- View this message in context: http://mailinglists.scilab.org/How-to-get-a-reguar-sampled-vector-in-Scilab-tp4028712.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
