Since your ultimate goal is to run a GSA on the model output, I would recommend the following:
- Create parameter outTimeScalar in your model with the relevant unit
- Create a parameter that converts the simulation time (which can be different for every simulation program) into the same unit as the parameter outTimeScalar. This can be achieved with a repeated assignment: timeInUnitOfInterest = time
- Create an observable that will call an external function that you will implement in the next step, for example: out = getOutput(timeInUnitOfInterest, speciesOfinterest, outTimeScalar)
- Create the external function that gives you the output at this specific time:
function out = getOutput(time, speciesOfinterest, outTime)
if all(time==0)
out = speciesOfinterest(end);
else
[time,idx] = unique(time,'last');
speciesOfinterest = speciesOfinterest(idx);
outTime = outTime(1);
out = interp1(time, speciesOfinterest, outTime,'pchip');
end
end
Please note that for this to provide meaningful results, you will need to make sure that timeInUnitOfInterest(1) < outTimeScalar < timeInUnitOfInterest(end).
Now, you can use Sobol GSA or MPGSA with outTimeScalar as an input that is sampled from a normal distribution.
I hope this helps.
Best regards,
Jérémy
Edit: Corrected function.
