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Question about warnings

#3640  Permalink Top

Question about warnings

Jul-18-13 13:47:48

Hello all

There are now some new warning messages including OMC parameter "+d=initialization" I would like to understand. Could you analise it?

Code:

Trying to fix over-determined initial system

========================================

Variables (0)

========================================

Equations (1, 1)

========================================

1/1 (1): 10.0 * v1 + 100.0 * v2 = 0.0

State Sets

========================================

no matching

record SimulationResult

...

end SimulationResult;

"Warning: Trying to fix over-determined initial system Variables 0 Equations 1... [not implemented yet!]

Warning: System is over-determined in Equations 1: 10.0 * v1 + 100.0 * v2 = 0.0;

Warning: Iteration variables with default zero start attribute in equation system:

         $DER.v1:DUMMY_DER(fixed = false ) .MyModel, .Real type: Real 

"

The model is:

Code:

model MyModel

    constant Real rho = 1000;

    constant Real g = 9.81;

    

    constant Real S1 = 10;

    constant Real S2 = 100;

    constant Real h = 50;

    

    Real m1(fixed = false);

    Real m2(fixed = false);

    Real x1(start = 5, fixed = true);

    Real x2(fixed = false);

    Real v1(start = 0, fixed = true);

    Real v2(start = 0, fixed = true);



equation

    m1 = rho*S1*(h + x1);

    m2 = rho*S2*(h + x2);

    S1*x1 + S2*x2 = 0;

    v1 = der(x1);

    v2 = der(x2);

    v1^2/2 + (h + x1)*(g + der(v1)) = v2^2/2 + (h + x2)*(g + der(v2));

end MyModel;

#3643  Permalink Top

Re: Question about warnings

Jul-19-13 18:57:54

I am also seeing:
Translation    14:39:36        0:0-0:0    The initial conditions are not fully specified. Use +d=initialization for more information.

I am not sure, from the warning, where or how to us +d=initialization?  Or how to set initial conditions so this warning going away.  Can anyone offer any guidance?
Does this just mean that some of the variables in my model need start=0.0 (or whatever is an appropriate value?). 

Thanks,

--Adam

#3644  Permalink Top

Re: Question about warnings

Jul-20-13 18:04:17

dersh wrote:

I am also seeing:
Translation    14:39:36        0:0-0:0    The initial conditions are not fully specified. Use +d=initialization for more information.

I am not sure, from the warning, where or how to us +d=initialization?  Or how to set initial conditions so this warning going away.  Can anyone offer any guidance?
Does this just mean that some of the variables in my model need start=0.0 (or whatever is an appropriate value?). 

Thanks,

--Adam

Hello dersh

To get the later messages +d=initialization was used.

Probably some "start" or "fixed" conditions are necessary. However I do not know where.

Best regards
Koldo

#3645  Permalink Top

Re: Question about warnings

Jul-20-13 22:26:54

I figured out something about that message.  If, in OMEdit, I select Preferences->Simulation I can then put in to OMC Flags:  +d=initialization
Then when I run, it shows the specific variables it is initializing.

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