Another issue about Linearize block
ck1313 opened this issue · 4 comments
I have another question about Linearize block.
In the MATLAB Function, line 68-79:
% log x_dot and y values
if LenPV == 1
if i == b;
x_dot_log(1) = x_dot;
y_log(1) = y;
end
else
if i > a && i<= LenPV + a+1;
x_dot_log(:, i - a) = x_dot;
y_log(:, i - a) = y;
end
end
When LenPV=1(only one disturbance variable) and i=2, x_dot_log(1) saved the baseline values. But no code to save the perturbed values. So we can not get the ABCD, when LenPV=1.
Good question. I played around with the block a bit and couldn't even figure out how this LenPV could be set to 1... The mask requires an input for X pert and U pert, and LenPV is the combined length of those two. I think this logic was placed in anticipation of an issue, but the issue looks like it sorts itself out and this code isn't used.
I did a few runs with the block to determine how it would react to a situation where the U pert was set to a number, but u was not being used to generate x_dot (ie. the single value case) and it returns B = 0, which makes sense. I also put in a 0 for U pert size and it returned a nan. I prefer the zero, so I would suggest placing a U pert value even if you have no U input.
If you have any specific issues with the Linearization block (situations where it fails) let me know so I can take a look.
I will leave this item open as a reminder to go back and clean up this section of code. Also, a statement in the block help should be added to discuss this situation.
Put in a 0 for U pert size and it returned a nan.
I think it is because line 103-104:
A = ABavg(:,1:LenX);
B = ABavg(:,LenX+1 :LenXU);
LenX = LenXU. We do not have (LenX+1 :LenXU), so the index bigger than dimensions. B is nan.
The same to D.
Is that not acceptable?
If a user is putting a 0 in for pert sizes they most likely made a mistake, so sending out a Nan seems ok to alert them that all is not well, though maybe a separate message would be more obvious.
closing this conversation out. If there is concern the issue was not addressed well enough and an error message should be added, feel free to open it back up.
Thanks,
-Jeff