When you estimate the model parameters from data, you obtain their nominal values that are accurate within a confidence region. The size of this region is determined by the values of the parameter uncertainties computed during estimation. The magnitude of the uncertainties provide a measure of the reliability of the model. You can compute and visualize the effect of parameter uncertainties on the model response in time and frequency domains.
present | Display model information, including estimated uncertainty |
simsd | Simulate linear models with uncertainty using Monte Carlo method |
freqresp | Frequency response over grid |
rsample | Random sampling of linear identified systems |
showConfidence | Display confidence regions on response plots for identified models |
getcov | Parameter covariance of identified model |
setcov | Set parameter covariance data in identified model |
translatecov | Translate parameter covariance across model transformation operations |
step | Step response plot of dynamic system; step response data |
stepplot | Plot step response and return plot handle |
impulse | Impulse response plot of dynamic system; impulse response data |
bode | Bode plot of frequency response, or magnitude and phase data |
bodemag | Magnitude-only Bode plot of frequency response |
nyquist | Nyquist plot of frequency response |
nyquistplot | Nyquist plot with additional plot customization options |
iopzmap | Plot pole-zero map for I/O pairs of model |
iopzplot | Plot pole-zero map for I/O pairs and return plot handle |
simsdOptions | Option set for simsd |
Plot Impulse and Step Response Using the System Identification App
To create a transient analysis plot in the System Identification app, select the Transient resp check box in the Model Views area.
Plot Bode Plots Using the System Identification App
To create a frequency-response plot for linear models in the System Identification app, select the Frequency resp check box in the Model Views area.
Plot the Noise Spectrum Using the System Identification App
To create a noise spectrum plot for parametric linear models in the app, select the Noise spectrum check box in the Model Views area.
Plot the Noise Spectrum at the Command Line
To plot the disturbance spectrum of an input-output model or
the output spectrum of a time series model, use spectrum.
Model Poles and Zeros Using the System Identification App
To create a pole-zero plot for parametric linear models in the System Identification app, select the Zeros and poles check box in the Model Views area.
Compute model parameter uncertainty of linear models.