ThreeSpecies_Quiescent: set initial_population parameter as start value of population #471
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The population variable is protected and setting the start value only works when using the FixedPopulation initialization. When using InitializationOptions.SteadyState, the start value is not adjusted (as in the ThreeSpecies_Quiescent example, which does not find the correct solution for me using OpenModelica). With this change, all examples work for me.
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The
ThreeSpecies_Quiescentexample seems to be broken usingOpenModelica v1.24.0-dev-164-g537f41ed82, probably due to the changes to theProtectedsection of models in Modelica, see #453. This PR suggests a solution by adjusting the start value.The population variable is protected and setting the start value only works when using the
FixedPopulationinitialization, then it is set using:ModelicaBook/ModelicaByExample/Components/LotkaVolterra/Components/RegionalPopulation.mo
Lines 18 to 19 in b07a59e
When using
InitializationOptions.SteadyState, the start value is not adjusted and the trivial solution is found instead of the non-zero solution.Only the derivative is adjusted:
ModelicaBook/ModelicaByExample/Components/LotkaVolterra/Components/RegionalPopulation.mo
Lines 20 to 21 in b07a59e
And for the start guess, the following line is still used:
ModelicaBook/ModelicaByExample/Components/LotkaVolterra/Components/RegionalPopulation.mo
Line 16 in b07a59e
With the following change, all examples seem to work correctly for me: