Archived OpenModelica forums. Posting is disabled.

Alternative forums include GitHub discussions or StackOverflow (make sure to read the Stack Overflow rules; you need to have well-formed questions)


Forgot password? | Forgot username? | Register
Page Start Prev 1 Next End

'failed to elaborate expression' in equation section with ext func.

#7185  Permalink Top

'failed to elaborate expression' in equation section with ext func.

Sep-27-16 21:58:58

Hello,

I've got a model that giving me a Translation Error.  I can't tell too much about the problem from the error message:

[1] 16:49:53 Translation Error
[PodRunSim.Components: 23:5-23:74]: Failed to elaborate expression: .PodRunSim.Utilities.getEddyBrakeData(con, v, h, f_drag, f_lift, H_y_max, H_y_mean, q_max, q_mean).

[2] 16:49:53 Translation Error
Error occurred while flattening model PodRunSim.Examples.HelloPodRunSim

The model is HelloPodRunSim in the dev branch of this repo: https://github.com/adamLange/podRunSim

What might be causing this error?

Adam

#7186  Permalink Top

Re: 'failed to elaborate expression' in equation section with ext func.

Sep-28-16 06:22:56

My guess is because the function is declared to take only 3 inputs.

#7188  Permalink Top

Re: 'failed to elaborate expression' in equation section with ext func.

Sep-28-16 21:22:51

There are only three inputs.  f_drag, f_lift, H_y_max, H_y_mean, q_max, q_mean are all outputs.

Code:


function getEddyBrakeData

    input EddyBrakeConnection con;

    input Real v;

    input Real h;

    output Real f_drag;

    output Real f_lift;

    output Real H_y_max;

    output Real H_y_mean;

    output Real q_max;

    output Real q_mean;

    external "C" getEddyBrakeData(con,v,h,f_drag,f_lift,H_y_max,H_y_mean,q_max,q_mean) annotation(

        Library="eddybrakeclient",

        LibraryDirectory="modelica://PodRunSim/ExternalLibraries");

  end getEddyBrakeData;

The c function is defined as follows:

Code:

int getEddyBrakeData(void* object,

  double v,double h,

  double* f_drag,double* f_lift,

  double* H_y_max,double* H_y_mean,

  double* q_max,double* q_mean)

The outputs are written to wherever the pointer point.

Would it be better if return the outputs as an array?

#7189  Permalink Top

Re: 'failed to elaborate expression' in equation section with ext func.

Sep-28-16 21:33:56

I think I found the answer in the Modelica specification version 3.3 revision 1 section 12.9.5.2:

12.9.5.2 Arbitrary Placement of Output Parameters, No External Function Value
[In the following example, the external function call is given explicitly which allows passing the arguments in a
different order than in the Modelica version.

Code:


function foo

input Real x;

input Integer y;

output Real

u1;

output Integer u2;

external "C" myfoo(x, u1, y, u2);

end foo;

This corresponds to the following C-prototype:

Code:


void myfoo(double, double *, int, int *);

Example call in Modelica:

Code:

(z1,i2) = foo(2.4, 3);

Translated call in C:

Code:

myfoo(2.4, &z1, 3, &i2);

]

#7190  Permalink Top

Re: 'failed to elaborate expression' in equation section with ext func.

Sep-28-16 21:42:55

Yep, that was it:

In a component I tried to call the external function with the "c" call signature and this generated the error failed to elaborate expression:

Code:

equation

  getEddyBrakeData(con,v,h,f_drag,f_lift,H_y_max,H_y_mean,q_max,q_mean);

  ...

I changed the modelica code to this and now there's no problem!:

Code:

equation

  (f_drag,f_lift,H_y_max,H_y_mean,q_max,q_mean) = getEddyBrakeData(con,v,h);

  ...

Page Start Prev 1 Next End
Previous topic
Next topic
There is 1 guest and 0 other users also viewing this topic
You are here: