Derivative of function :: OpenModelica

Derivative of function

Jun-21-10 10:43:18

Hi,

I am trying to find the derivative of the function. I have used the annotation that enables the derivative property of the function. As an example I tried the following code (given to me by the openModelica support)

function my_abs annotation(derivative=my_abs_der);
input Real r;
output Real out = abs(r);
end my_abs;

function my_abs_der
input Real r;
input Real der_r;
output Real out;
algorithm
out := abs(r)*der_r;
end my_abs_der;

class M
Real r = my_abs(15.0*time);
Real der_r = der(r);
end M;

I am getting the following error in SimForge

{"",""}
"Error: The language feature differentiation of function my_abs is not supported. Suggested workaround: no suggestion
Error: Derivative of expression my_abs(15.0 * time) is non-existent
Error: Model is structurally singular, error found sorting equations r = my_abs(15.0 * time); for variables "

Please give some suggestions

Thank you

John

jkocherry: 21 Posts; Thank you [ 0 ]

#322 Permalink

Re: Derivative of function

Jun-21-10 10:47:38

What version of OpenModelica are you using? The code runs fine in the trunk.

sjoelund.se: 1700 Posts; Thank you [ 159 ]

#323 Permalink

Re: Derivative of function

Jun-21-10 11:07:08

I am using the OpenModelica 1.5.0 RC3

jkocherry: 21 Posts; Thank you [ 0 ]

#324 Permalink

Re: Derivative of function

Jun-21-10 12:03:40

Ah. RC3 is from April 22. Jens Frenkel fixed derivative annotations after that release.

sjoelund.se: 1700 Posts; Thank you [ 159 ]

#325 Permalink

Re: Derivative of function

Jun-21-10 13:23:08

Is there a release after that?

I tried running them from shell and am still getting the same errors. I have been on this for sometime

jkocherry: 21 Posts; Thank you [ 0 ]

#326 Permalink

Re: Derivative of function

Jun-21-10 13:29:03

There is no Windows binary release after RC3 (the Linux one is from May14 though).
The source in the subversion trunk is always up to date.

sjoelund.se: 1700 Posts; Thank you [ 159 ]

#327 Permalink

Re: Derivative of function

Jun-21-10 15:14:01

So how do I check if it is updated?

Can you suggest a way to get this one working?

jkocherry: 21 Posts; Thank you [ 0 ]

#328 Permalink

Re: Derivative of function

Jun-21-10 15:18:22

https://openmodelica.org/index.php/deve … ource-code - check out a version and read the instructions on how to compile it (README-OMDev-MINGW.txt). Or wait a few days and hope Adrian has pushed a new OpenModelica release.

sjoelund.se: 1700 Posts; Thank you [ 159 ]

#329 Permalink

Re: Derivative of function

Jun-22-10 07:42:07

So does that mean I cant run it on this version of OpenModelica??

When is the next release scheduled?

Thank you very much for the continuous support and prompt replies

jkocherry: 21 Posts; Thank you [ 0 ]

#330 Permalink

Re: Derivative of function

Jun-22-10 07:44:21

The 1.5.0 release should be once the documentation has been updated, hopefully this week.

sjoelund.se: 1700 Posts; Thank you [ 159 ]

#350 Permalink

Re: Derivative of function

Jul-05-10 09:14:03

Any update on the release of the latest version of OpenModelica? Will it be supporting the media library?

We are waiting..........:-)

Thank you

John

jkocherry: 21 Posts; Thank you [ 0 ]

#351 Permalink

Re: Derivative of function

Jul-05-10 09:16:48

Not much support for Modelica.Media (that is to say: nothing works). This release is more focused on Modelica.Mechanics.MultiBody (which flattens code but can not yet simulate all models).

sjoelund.se: 1700 Posts; Thank you [ 159 ]

#352 Permalink

Re: Derivative of function

Jul-05-10 09:27:26

The derivative annotations for a function now works.
As far as I know (from Jens Frenkel) some of the MultiBody models (Pendulum, DoublePendulum) now actually simulate.

Cheers,
Adrian Pop/

adrpo: 885 Posts; Thank you [ 141 ]

#353 Permalink

Re: Derivative of function

Jul-05-10 09:58:30

So the support for the function derivatives will be added in the new release or is it already supported in RC3?

When can we expect the new release? I am working on some projects and want to plan the deadlines based on this.

Thank you

John

jkocherry: 21 Posts; Thank you [ 0 ]