Documentation Center

  • Trial Software
  • Product Updates

Uncertain Real Parameters

An uncertain real parameter is the Control Design Block that represents a real number whose value is uncertain. Uncertain real parameters have a name (the Name property), and a nominal value (the NominalValue property). Several other properties (PlusMinus, Range, Percentage) describe the uncertainty in parameter values.

All properties of a ureal can be accessed through get and set. The properties are:

Properties

Meaning

Class

Name

Internal name

char

NominalValue

Nominal value of element

double

Mode

Signifies which description (from'PlusMinus', 'Range', 'Percentage') of uncertainty is invariant when NominalValue is changed

char

PlusMinus

Additive variation

scalar or 1x2 double

Range

Numerical range

1x2 double

Percentage

Additive variation (% of absolute value of nominal)

scalar or 1x2 double

AutoSimplify

'off' | {'basic'} |'full'

char

The properties Range, Percentage and PlusMinus are all automatically synchronized. If the nominal value is 0, then the Mode cannot be Percentage. The Mode property controls what aspect of the uncertainty remains unchanged when NominalValue is changed. Assigning to any of Range/Percentage/PlusMinus changes the value, but does not change the mode.

The AutoSimplify property controls how expressions involving the real parameter are simplified. Its default value is 'basic', which means elementary methods of simplification are applied as operations are completed. Other values for AutoSimplify are 'off' (no simplification performed) and 'full' (model-reduction-like techniques are applied). See Simplifying Representation of Uncertain Objects to learn more about the AutoSimplify property and the command simplify.

If no property/value pairs are specified, default values are used. The default Mode is PlusMinus, and the default value of PlusMinus is [-1 1]. Some examples are shown below. In many cases, the full property name is not specified, taking advantage of the case-insensitive, partial name property matching.

Was this topic helpful?