compute properties of a step response
StepProperties( sys, opts )
System; a system object
(optional) equation(s) of the form option = value; specify options for the StepProperties command
parameters = set(name = complexcons) or list(name = complexcons)
Specifies numeric values for parameters in sys. These values override those specified by the parameters field of the system object, which in turn override the settings in in SystemOptions(parameters). The numeric value on the right-hand side of each equation is substituted for the name on the left-hand side in the expressions that define the model. No checking is done during the substitution to determine whether the substituted value is valid. For example, a complex value can be substituted for the coefficient of a polynomial. If the complex value had been originally assigned to the model at creation, a warning would be generated.
duration = numeric
Specifies the time duration in which to search. If not specified, a suitable value is computed.
no_evalf = truefalse
True means do not use evalf when substituting symbolic parameters in the system. This may be useful when the values are exact (integers or fractions). The default is false.
ret_record = truefalse
True means return a record of values, rather than a list. The default is false.
The StepProperties command calculates the unit-step response properties of a system object, sys, where this object must be linear and stable. Both continuous and discrete objects are accepted.
It returns an expression sequence: (final-value, 10%-point, 33%-point, 67%-point, 90%-point, peak-point, settling-point).
The first element in the sequence (final-value) is a single value. Each of the remaining elements is a list of two values, the time or index of the point and the associated value of the step response.
If the step-size is zero, a warning is raised and the percentage points will be undefined.
This list describes each of the properties returned.
Final-value: the steady-state value of the step response.
10%-point: where response first reaches 1/10 to the final value.
33%-point: where response first reaches 1/3 to the final value.
67%-point: where response first reaches 2/3 to the final value.
90%-point: where response first reaches 9/10 to the final value.
peak-point: where response first reaches the peak value If the peak does not occur, [undefined, undefined] is returned. If the step is negative, the peak is in the negative direction. If the step-size is zero, the peak is at the greatest excursion from the initial value, regardless the direction.
settling-point: the settling point of the step response. If the settling time is not found within the given interval, [undefined, undefined] is returned.
Ts ≔ 0.05
Duration of simulation
dur ≔ 10
Number of samples
Ns ≔ round⁡durTs
sys ≔ TransferFunction⁡1s2+s+10
sys≔Transfer Functioncontinuous1 output(s); 1 input(s)inputvariable=u1⁡soutputvariable=y1⁡s
prop ≔ StepProperties⁡sys
10% to the final value
33% to the final value
67% to the final value
90% to the final value
sysz ≔ ToDiscrete⁡sys,Ts
sysz≔Transfer Functiondiscrete; sampletime = .5e-11 output(s); 1 input(s)inputvariable=u1⁡zoutputvariable=y1⁡z
propz ≔ StepProperties⁡sysz
tfs ≔ subs⁡Ts_=Ts,x→x1−1⁢Ts_,x2
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