If sys is a model array, then params is a
cell array of parameter value vectors corresponding to each model in
sys.
params is [] for
idnlarx and idnlhw models that have not been
estimated.
Standard deviation values for parameters, returned as a vector.
If sys is a model array, then stdDev is a
cell array of standard deviation value vectors corresponding to each model in
sys.
If the model covariance information for sys is not available,
then stdDev is []. As a result,
stdDev is always [] for
idnlarx and idnlhw models because these
models do not store parameter covariance information.