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derivative annotation doubt
derivative annotation doubt
Hello all
I have questions about the use of "derivative" annotation I wanted to ask you. Lets put a sample.
The equation is this:
Code:
z_level = LevelZ(time);
where LevelZ(time) is an external C function, and there are also LevelZ_der(time) and LevelZ_der2(time) that are the first and second derivative.
It the code is like this, it works well...
Code:
function LevelZ_der2
input Real t;
input Real dt;
input Real ddt;
output Real res;
external
res = LevelZ_der2(t);
annotation(Library="...", Include="...");
end LevelZ_der2;
function LevelZ_der
input Real t
input Real dt
output Real res;
external
res = LevelZ_der(t);
annotation(derivative=LevelZ_der2,
Library="...", Include="...");
end LevelZ_der;
function LevelZ
input Real t
output Real res;
external
res = LevelZ(t)
annotation(derivative=LevelZ_der,
derivative(order=2)=LevelZ_der2,
Library="...", Include="...");
end LevelZ;
... although these errors appear:
Code:
[C:/Users/Model/Model.mo:52:2-52:28:writable] Warning: Unused input variable dt in function .LevelZ_der2.
[C:/Users/Model/Model.mo:52:2-52:28:writable] Warning: Unused input variable ddt in function .LevelZ_der2.
[C:/Users/Model/Model.mo:52:2-52:28:writable] Warning: Unused input variable dt in function .LevelZ_der.
Error: Derivative of expression
Differentiate.differentiateExpSolve failed for z_level - LevelZ(time)
is non-existent.
And if the code is like this, OpenModelica ignores the derivatives...
Code:
function LevelZ_der2
input Real t;
output Real res;
external
res = LevelZ_der2(t);
annotation(Library="...", Include="...");
end LevelZ_der2;
function LevelZ_der
input Real t
output Real res;
external
res = LevelZ_der(t);
annotation(derivative(zeroDerivative=t)=LevelZ_der2,
Library="...", Include="...");
end LevelZ_der;
function LevelZ
input Real t
output Real res;
external
res = LevelZ(t)
annotation(derivative(zeroDerivative=t)=LevelZ_der,
derivative(order=2)=LevelZ_der2,
Library="...", Include="...");
end LevelZ;
... and this error appear:
Code:
Error: Derivative of expression
Differentiate.differentiateExpSolve failed for z_level - LevelZ(time)
is non-existent.
What is the right way to do it?
Best regards
Koldo
Thank you
Re: derivative annotation doubt
"Error: Derivative of expression
Differentiate.differentiateExpSolve failed ..." error message is got for almost all external functions called, even the simplest:
netpower = power*Performance(speed);
where while "power" and "speed" are obtained by solving differential equations, Performance() is a "pure" external function and "netpower" is just an output.
Do you now how to solve this?
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