from:"Michael J. McCann"

Re: [Scilab-users] Sundials module, Windows preview

2022-05-15 Thread Michael J. McCann

Currently I'm not using the ODE solvers but it's an area of interest 
since mathematical modelling is the core of my business. I'd like to see 
that in Xcos I can get the full range of ODE solvers (at least for 
'real-only' as distinct from 'complex-number' issues).



On 13/05/2022 12:03, Federico Miyara wrote:


Stéphane,

I don't regularly use ODE solvers for the time being, but I think any 
improvement is valuable and is worth the effort. The lack or paucity 
of feedback in this list is not an evidence of lack of interest for 
the Scilab users community. It may also encourage other potential 
users to move to Scilab. I'm grateful for your effort and feel 
reassured that in the event I need the feature, I'll have better solvers.


Regards,

Federico Miyara

On 13/05/2022 11:45, Stéphane Mottelet wrote:


Hello,

Did anybody give a try to the Windows build ?

Frankly speaking, if nobody cares about improved numerical methods in 
Scilab, things can be left as is, and time could be spent on other 
features (but not by me...).


I can also prepare a Linux build, if users of this os want to test...

Regards,

S.

Le 27/04/2022 à 17:32, Stéphane Mottelet a écrit :


Hi all,

The next version of scilab will include a new module "Sundials". 
This module provides new full featured  ODE solvers: arkode(), 
cvode() and DAE solver ida(), all handling complex numbers and 
dense/sparse/banded Jacobians. Each solver has specific features, 
e.g. ida() handles DAE, arkode() handles mixed implicit/explicit 
Runge-Kutta methods and cvode() can do forward sensitivity computation.


The module also includes a general-purpose nonlinear system solver: 
kinsol(), who takes advantage of the module architecture (parsing, 
computation engine and SUNDIALS abstraction of various linear solvers).


Current help pages can be found @ 
https://www.utc.fr/~mottelet/scilab/sundials/ and a *Windows* build 
of Scilab (in addition to the already available macOS build) 
including the new module is available at


https://www.utc.fr/~mottelet/scilab_for_macOS.html

The help pages propose a lot of examples and two demos (this section 
is to be enriched) are available.


Comments are welcome !

--
Stéphane Mottelet
Ingénieur de recherche
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
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Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
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http://www.utc.fr/~mottelet

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Re: [Scilab-users] FEA in Scilab

2020-01-30 Thread Michael J. McCann


Federico,
This isn't really an answer but I have in hand a book;

"Introduction to  Finite and Spectral Element Methods Using MATLAB",
 C.Pozrikidis, CRC Press,    2014     ISBN978.1.4822.0915.0
It might provide models for coding even if the dialect is different.

Mike.

On 1/28/2020 7:14 PM, Federico Miyara wrote:


Claus,

I'm interested.

Regards,

Federico Miyara


On 27/01/2020 07:25, Claus Futtrup wrote:

Dear fellow Scilabers

There are various initiatives and possibly demonstration projects for 
implementing Finite Element algorithms and Analysis in Scilab. Please 
help me by providing pointers.


What I'd like to simulate is the suspension of a loudspeaker (the 
cloth spider which essentially centers the voice coil in the air 
gap), in particular I wish to calculate a force-deflection curve.


In my particular case, I'd like to describe the spider as a 
collection of line segments (straight lines as well as circular 
sections). This description represents a cross section view of the 
spider. For proper modeling, this is an axisymmetric model of the spider.


I have a simple description of what I'd like to do in Scilab, but 
done in a software named Mecway. The PDF is 650 kb (4 pages). I am 
worried about attaching such a document to the User Group here in 
general, but I can of course send it on request. In Mecway the 
axisymmetric model is expanded into 3D with hex8 elements (it looks 
like a basic cubic element). The force-function is applied in 40 time 
steps. It looks like 40 x basic static analysis.


Please let me know what you think would be suitable for solving this 
problem. Is there a suitable ATOMS library?


Best regards,
Claus

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Re: [Scilab-users] Win10.Scilab601.IPCV2.Not Loading

2018-08-21 Thread Michael J. McCann


TanChin,
Thank you. As the only person who ever uses this personal computer I 
never thought of using a program ' as administrator'  BUT did find the 
option to do that (I never tried rt-click on a shortcut before!). My 
impression was that Scilab couldn't find the pathways/gateways(?) which 
it needed to load the installed module.


However, I removed the IPCV2.0 and installed IPCV1.2 but only after 
discovering that

atomsInstall(["IPCV" "1.2"])  did not work BUT
atomsInstall(["IPCV", "1.2"]) worked fine.
I added the comma after something flagged that it was looking for a 
string as the first variable. So now I have a version working as used on 
the other machine and have also been able to share the work.

Thank you for the advice and the IPCV work you do.
Mike.
=

On 21/08/2018 02:10, Tan Chin Luh wrote:
Did you try to run the scilab with admin right? Do this by right-click 
on the scilab, run as administrator.



On 20/8/2018 7:29 PM, Michael J. McCann wrote:
I have Scilab6.01 on a Windows 10 machine. I have recently installed 
"IPCV" via Atoms. That went in OK but when I restart Scilab, the 
loading process only gets as far as  reporting, in the console,   ' 
load gateways'    and nothing more.
The IPCV functions don't work.   I can see that  [" IPCV,"2.0"] is 
installed.


I have IPCV working on a different Windows10machine with Scilab6.01 
BUT I suspect it is an earlier version of IPCV


Is this a bug with IPCV2 or have I missed something?
MikeMcC.
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[Scilab-users] Win10.Scilab601.IPCV2.Not Loading

2018-08-20 Thread Michael J. McCann

I have Scilab6.01 on a Windows 10 machine. I have recently installed 
"IPCV" via Atoms. That went in OK but when I restart Scilab, the loading 
process only gets as far as reporting, in the console,   ' load 
gateways'    and nothing more.
The IPCV functions don't work.   I can see that  [" IPCV,"2.0"] is 
installed.


I have IPCV working on a different Windows10machine with Scilab6.01 BUT 
I suspect it is an earlier version of IPCV


Is this a bug with IPCV2 or have I missed something?
MikeMcC.

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Re: [Scilab-users] unable to find my mistake in the function

2017-06-06 Thread Michael J McCann

Looks   a bit strange to me : in loop n=1:3,  t(1) is defined three 
times (may be OK)

but schritte could be  non integer so a bit odd for an index into an array.
Is the t() array being grown (size not previously defined)?
Mike.

On 06/06/2017 08:27, Sachverständigenbüro Niedermaier Holger wrote:

Dear all,
may anybody be able to explain why I get the error message "invalid 
index in line 12“ by running the following function?


function  [Wert]=Berechnungsfunktion(von,bis,schrittweite,y0,y2,t0,t2)
 for  n=1:3
 t(1)=t0;
 y(1,n)=y0;
 schritte=(bis-von)/schrittweite;
for  i=1:schritte
 t(i+1)=t(i)+schrittweite;
 
y(i+1,n)=10^(log10(y0*Faktor(n))+log10(y2/y0)/log10(t2/t0)*log10(t(i+1)/t0))
end
 disp(n)
 for  i=1:schritte
 Energie(n)=Energie(n)+y(i)*y(i)*schrittweite*10^(-3);
 end
 disp(Energie(n))
  end
 //disp("1 Polig",Energie(3),"2 Polig", Energie(1),"3 Polig", Energie(2))
 //Wert=[Energie];
endfunction
I myself be to blind to find my mistake
Thanks a lot
Holger


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Re: [Scilab-users] calculate TRMS value in Xcos

2017-05-19 Thread Michael J McCann


RMS Value:
In a dynamic system simulation you can readily generate an instantaneous 
power value that can be recorded  simply by using a volts*current 
product or any other dimensionally equivalent product.
If however you want to do some averaging of the power level then you 
must have a record of that instantaneous  value and do the averaging 
over the length of the record,  which your request implies you have and 
therefore implies a post processing operation. You can partition the 
record into whatever shorter lengths you want and generate true RMS 
values over those time segments. But beware, if the model is  simulating 
a fixed frequency  (e.g.50Hz) power system then the periods must be 
integer multiples of the cycle time.


If you want a value that appears like a metered  value might appear then 
you can put the product term through a 1st order lag (exponentially 
weighted effect)

  G(s)=1/(1+sT)   // xdot=(1/T)*(Input- x);
and imitate the behaviour of a meter. All you have to do is chose the 
"time constant",T, of the meter. e.g several cycles.


The MATLAB (2017a)  Moving RMS includes the exponential weighting option 
and the true moving window version as well. I expect it could be 
replicated in XCOS with a SciLab function.


Mike.
==

On 19/05/2017 05:51, Sachverständigenbüro Niedermaier Holger wrote:

Dear all,
by simulating an electrical power circuit I’d like to plot the voltage and the 
current over time, which is easy to perform by using the scope block.
In addition to the signal recorded I’d like to calculate the TRMS value of the 
plotted current and voltage signal.
Unfortunately Xcos does not include a TRMS block like e.g. Simulink do.
Because I’m so far not so familiar with Xcos and Scilab I’d like to ask the 
community for support.
Does anybody have a good idea or advise how to get the TRMS value of the 
recorded signal?
Thanks and nice weekend
Holger
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Re: [Scilab-users] Modelling dynamic systems with real world data

2017-04-13 Thread Michael J McCann

Hmm... batteries: Charge storage devices which have a largely constant 
voltage in the working range but which show big changes in apparent 
voltage when they reach full charge and when the charge drops very low. 
You don't get all the electrons back. I suspect a really good model 
would relate these effects to the electrochemical processes at work. 
Also because they are "batteries" and not individual cells,  the 
aggregate behaviour will depend on the whole (in series) set.
With a sort of diodes and resistors model for the charge and discharge 
routes (somewhat different characteristics), it is possible to make a 
fair model for a battery's functional operations but I'd be a bit 
concerned if it was to try to make predictions of behaviour under 
stress  (e.g.very high discharge rates) or temperature changes (which in 
lead acid batteries reduce apparent capacity and ability to deliver 
current). There's an industry emerging for batteries with all the 
associated support equipment for creating backups for solar power etc.

So it becomes a question of how deep you want to go into the physics.

Mike.

=
On 12/04/2017 16:02, t...@wescottdesign.com wrote:

I strongly suspect that anything that would be useful would be 
specific to batteries, and would perhaps be best done in batch mode to 
generate a model that is then hand-tweaked and selected for use in 
xcos -- but I say that in part because over the years I've come to 
dislike graphical solvers.

I think it's possible to build a subsystem out of blocks that can be 
"masked" so that you can enter parameters in the usual way -- if you 
could boil your battery model down so that it had a few parameters, 
you could translate your measured data into parameters once, then use 
parameterized blocks for the battery behavior.

On 2017-04-12 07:49, phillip mobley wrote:

Sure thing Tim,
Thank you for pointing out those details. I will share as much as I can.
I am simulating the behavior of a battery as it is discharging into a 
circuit. I recorded data from the battery (for example, the voltage 
and current and internal resistance) during testing. I currently have 
the data at different time steps inside of an excel file.
I would like to test this battery under different circuit 
configurations. However, changing the circuit can be time consuming 
and expensive. I was thinking that I could use xcos ability to do 
circuit simulation to construct a basic model of the battery that I 
am using that utilizes the data that I gathered. This way I can 
simulation the battery under different circuit configurations very 
easily.
So I was wondering if there was a way that I could import my data 
into xcos to construct a model for simulation.

I actually created the system to simulate the battery.

On Tue, Apr 11, 2017 at 3:48 PM, Tim Wescott > wrote:

"Simulate the data"?

Surely you mean you wish to simulate the system which was used in the
measurement!

You don't give much detail, but I suspect that what you want to do is
to develop a model of the system that fits the experiment, and
then use
that model in your simulations.

The general term for generating the model is called "system
identification", but that covers a pretty broad swath.

Can you share the test you did, the sort of data you collected, the
sort of system you're trying to model, and how well you know the
system
itself?

On Tue, 2017-04-11 at 15:10 -0400, phillip mobley wrote:
> Hello all,
>
> I have some data from a test that I preformed. I was looking to
> simulate this data under different conditions and I was
wondering if
> there is a palette in xcos that would allow me to input data (maybe
> from an excel spreadsheet or copy paste) in order to use in the
> simulation?
>
> Is this possible with xcos?
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www.wescottdesign.com 
Control & Communications systems, circuit & software design.
Phone: 503.631.7815 
Cell: 503.349.8432 

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Re: [Scilab-users] Variable Capacitor

2017-02-20 Thread Michael J McCann

Just a thought... I don't know about the model component you are using 
but if you change the value of a capacitor while it is charged the 
voltage changes. So choosing the value for a component in a circuit is 
one thing. Dealing with a charged capacitor which changes can produce 
some interesting effects. Conservation of charge and energy balance must 
be considered.

Mike.
===

On 20/02/2017 16:10, Theo D. wrote:

Thank you very much Samuel !



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Re: [Scilab-users] Phase shift and step size - electrical (XCOS)

2016-04-02 Thread Michael J McCann

I mostly use Matlab and Simulink or my own software but I can see that
in Xcos I can define parameters that control parameters inside the
blocks. The Simulation menu item in Xcos has the option to define the
integration method and there are some choices you can make about maximum
stepsize for Runge Kutta, which is basically a fixed step approach but
they may be embedding it in a variable step size environment so it will
make adjustments (to smaller steps). There is within the [Simulation]
item a [Set Context] option that allows you to deliver numeric values
into the simulation as well. Also, I suspect that if you specify a clock
to drive the sampling of a "scope" you can implicitly define a maximum
step size.
With regard to the operations of multiply and divide I'd say "be
careful" because a division is a strange thing to have in a real
physical system so I'd be looking at your understanding of the system
you were modelling and ask why it appears at all.

Hope this helps
Mike McCann
www.mccannscience.com/mcsimapn.htm

On 01/04/2016 18:41, laftek wrote:

Hi there. I see nobody is responding. Could somebody at least help me with
step size ? Is there any chance I can set it manually ? This is what I mean.

Could you help with Singularity in a block either? If I use mathematical
operator : multiplication

I am getting error : Singularity in a block. But if I use instead this one

I am not longer getting singularity problem. Is there some workaround for
division block ? I tried to use PROD_f with u^-1 or 1/u but nothing works. I
really need it

Thanks !

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Re: [Scilab-users] Simulation of static general equilbiirum model

2014-09-27 Thread Michael J McCann

In general this is not a 'simulation' problem. Static equilibrium 
involves no dynamics, but I have in the past used analog computing ideas 
to get to a static equilibrium because the system  was intrinsically 
stable.


If you have (or can create)  the underlying differential equations and 
are looking for their equilibrium then you can just let it run till it 
settles to the steady state. A trick is to ignore the coefficients of 
the  dx/dt terms and make them all the same e.g. unity  and then the 
convergence can be speeded up. When you have done all that you have a 
sort of successive approximation method for equilbrium but really you 
should be getting help from someone who will guide you into the usual 
numerical techniques e.g Newton Raphson.

Mike.
==
On 2014-09-27 9:32, Mathseco wrote:

Hi i'm new to scilab !!!

I have a static general equilibrium model with 8 endogenous variable and 8
independent equations.

Can anyone guide me how to do simulation of such model in scilab ? I want to
get the values of endogenous variable in the model by solving those
equations for different values of exogenous variables.Please guide
meThanks



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Re: [Scilab-users] Recognition of cursor key as input

2014-08-12 Thread Michael J McCann

I don't know if this will help but I wrote simulation software in Pascal 
and so that it could respond to mouse clicks anywhere while running it 
made a check to look for it at the end of  every single integration 
step. I guess you might be able to check for keyboard input repeatedly. 
Mike.

On 2014-08-11 8:52, Jens wrote:

Hello Philipp,
I'm aware of messagebox, x_dialog or x_choices. I fear the abbreviated
way I'm looking for does not exist.
Kind regards
Jens



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Re: [Scilab-users] Bicycle Dynamics

2014-05-15 Thread Michael J. McCann


Note my official Scilab address is via mjmcc...@ieee.org (IEEE in US)
but my email client uses my address mjmcc...@iee.org  (IEE now 
IET, in UK)


If you are interested in bicycle dynamics, stability and control you 
should look at the special edition of the IEEE Control Systems Magazine, 
October 2006, Volume 26 number 5, Advances in Motorcycle Design and 
Control There are hundreds of references going back to the late 1800s.  
Key authors in this journal were Alessandro Beghi and Ruggero Frezza, 
also David J. N. Limebeer and Robin S. Sharp. I happened  to keep a copy 
for personal interest, but I haven't worked in this field. It's all 
there, stability, wobble, weaving, shimmy, stabilization methods and 
geometry effects. On page 110 there's a picture of Albert Einstein 
turning a corner on a bicycle with his quote, Life is like riding a 
bicycle. To keep your balance you must keep moving.


Thinking about the problem discussed here in Scilab/Xcos it seems to me 
that you are interested in the rotation about the contact line with the 
road, that the radius of gyration will be dominated by the height of the 
rider's  CG above the road unless it's a motor bike in which case the 
mass of the bike could well dominate the analysis and furthermore, since 
turning involves rotation about a vertical axis and at high speed, the 
wheels can have significant angular momentum (gyroscopic effect) you may 
have to consider the angular momentum in 3 space. Good luck.


Mike.
Dr. M.J. McCann,
MJMcCann Consulting

 On 14/05/2014 09:16, Dang, Christophe wrote:

it seems to me it should be
mg*l*cos(theta) - (mv^2/r)*l*sin(theta)
and not the contrary.

Or?

Or not.
Sorry, you're right, I messed the axes up.
A shame for someone writing Mechanical calculation engineer in his signature 
;-)

So, your calculation seems globally right.

Now, your question If anyone could confirm that the model seems to be realistic/ or 
correct is not obvious:
I ride my bike everyday to go to work, and if I have a pulse in the steering 
angle, I correct it with my balance...

Not sure 'bout what I'm saying (and I wrote enough silly things yet), but once 
delta goes back to 0, r is back to infinity (straight movement),
so what you should see is the biker falling.

--
Christophe Dang Ngoc Chan
Mechanical calculation engineer




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Re: [Scilab-users] Convert x, y, z data into a z=f(x,y) function

2013-07-01 Thread Michael J. McCann


Larisssa,
Now we have a clue. Many years ago I worked on dynamic system models of 
fermentation. What I did was to create a differential equation set to 
account for the identifiable species --- abstract idea which includes 
various bio-chemical generic classes -- and running those models and 
experimenting it became possible to get a working model, by choosing 
parameters.  When that reached its limit, moving on to more complex 
models enabled us (me and a micologist) to create a model good enough to 
predict the performance of an industrial process.
In your case I'd start with a very simple model, and I'd expect 
that since the growth rate in biomass would initially probably increase 
in proportion to the mass present the model would give an exponential 
initial rate, then as the algae blocked the light it wanted and the 
other key food sources (dissolved oxygen?) were depleted, the rate would 
decline. In the work I did in the past we got into the metabolic 
pathways and  energy balances with heat and synthesis reaction rates, 
but I'd start with something simpler in your case to see how simple a 
model would explain the process. I would be a good candidate for a model 
in Xcos. You can look into my website

http://www.mccannscience.com/fermenta.htm
if you are interested.
Mike
===
On 01/07/2013 09:24, Larissa wrote:

Hi,
so regarding the data..
it was an experiment related to algal biomass yield (g/m²) (z) 
according to time (0-25days, the x-data) and light intensity 
(25-1000µmol*m^-1*s^-1, the y values). Increase in biomass might 
have been exponential right at the beginning, but with increasing time 
I guess it turned out to be linear...

does anybody have a hint about the model I could use?:)
*Gesendet:* Montag, 01. Juli 2013 um 11:14 Uhr
*Von:* Mike Page [via Scilab / Xcos - Mailing Lists Archives] 
[hidden email] /user/SendEmail.jtp?type=nodenode=4026926i=0
*An:* Larissa [hidden email] 
/user/SendEmail.jtp?type=nodenode=4026926i=1

*Betreff:* Re: Convert x, y, z data into a z=f(x,y) function
?
Hi,
You are asking a question which in general has no answer. There are an 
infinite number of models which can fit your data.  You need to find 
some possible candidate model forms based on physical properties and 
then try fitting to them.  You are probably looking for a fit which 
leaves residues which are Gaussian and mean zero (but that's not 
always true...).
Try giving us a clue about where the data come from.  Maybe somebody 
has the physical background to suggest some models.  If not, try 
plotting the data and guessing a model from the shape.  To me the 
shape looks vaguely exponential or logarithmic, so maybe plotting as 
log-linear or log-log will give a clue.

HTH,
Mike.

-Original Message-
*From:* [hidden email] [mailto:[hidden email]]*On Behalf Of
*Larissa Schultze
*Sent:* 01 July 2013 09:43
*To:* International users mailing list for Scilab.
*Subject:* Re: [Scilab-users] Convert x, y, z data into a z=f(x,y)
function
Hello all,
first of all, thanks a lot for your effort. I must say that I
don't really have anyone to run to for asking about mathematical
models - I could go to the mathematicians at the University, but I
don't know anyone there and I barelly know where the institute is
located...
therefore I decided to insert my simplest table in here (it is
actually very simple) - may be someone here knows which kind of
mathematical model I could use?
I have been searching for it in literature, but I don't seem to be
in the right path...
So attached you will find my data table as well as the scilab
commands I used to create the respective graph. I mean, my data is
already interpolated...shouldn't it be easy to get a function
(z,x,y) out of it?
I would be very very thankful for any help...I'm getting a bit
desperate...
best regards,
Larissa
*Gesendet:* Dienstag, 25. Juni 2013 um 11:09 Uhr
*Von:* CRETE Denis [hidden email]
*An:* International users mailing list for Scilab. [hidden email]
*Betreff:* Re: [Scilab-users] Convert x, y, z data into a z=f(x,y)
function
Hello,

The general procedure for fitting data in the case of 2 variables
is the following:
// First define your mathematical model by changing the following line
deff('z=MyFunction(x,y)', 'z=p(1)*x + p(2)*y + p(3)*x.*y');
// Store all experimental data in a single array ExD; X, Y, Z
assumed to be 1 x NZ vectors
ExD=[X;Y;Z];
// Define the error function (to be minimized with respect to the
parameters p)
deff('erro=G(p,ExD)','x=ExD(1),y=ExD(2), z=ExD(3),
erro=z-MyFunction(x,y)')
// Fit experimental data contained in W
// The column vector p0 is an initial guess of the values for the
parameters of your Model
[p,err]=datafit(G,ExD,p0)
// you can check values generated with
MyFunction(X,Y)

HTH
Denis

Re: [Scilab-users] Docking Console SciLab5.4 newuser

2013-04-24 Thread Michael J. McCann


Stanislaw,
Thank you. That works well.  I would add that until the cursor 
doing the dragging gets over the target window there is no sign of 
movement. That might make some people think the move wasn't working.

Thanks again, Mike.
On 24/04/2013 23:15, Станислав wrote:

24.04.2013 21:07, Michael J. McCann пишет:
My new Scilab5.4.1 opened up beautifully with the console docked 
between other panels.
Accidentally I undocked the console  by clicking on the little arrow 
(top right).

Now I can't get it or any of the other panels back together.
Do I have to reinstall the whole thing?

Hi.
See here http://www.equalis.com/forums/posts.asp?topic=560519;

Stanislav
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