Robust Control Toolbox™

Create uncertain complex parameter

Syntax

• A = ucomplex('NAME',nominalvalue) 
  A = ucomplex('NAME',nominalvalue,'Property1',Value1,...
           'Property2',Value2,...) 
  

Description

An uncertain complex parameter is used to represent a complex number whose value is uncertain. Uncertain complex parameters have a name (the Name property), and a nominal value (the NominalValue property).

The uncertainty (potential deviation from the nominal value) is described in two different manners:

• Radius (radius of disc centered at NominalValue)
• Percentage (disc size is percentage of magnitude of NominalValue)

The Mode property determines which description remains invariant if the NominalValue is changed (the other is derived). The default Mode is 'Radius' and the default radius is 1.

Property/Value pairs can also be specified at creation. For instance,

• B = ucomplex('B',6-j,'Percentage',25) 
  

sets the nominal value to 6-j, the percentage uncertainty to 25 and, implicitly, the Mode to 'Percentage'.

Example

Create an uncertain complex parameter with internal name A. The uncertain parameter's possible values are a complex disc of radius 1, centered at 4+3j. The value of A.percentage is 20 (radius is 1/5 of the magnitude of the nominal value).

• A = ucomplex('A',4+3*j) 
  Uncertain Complex Parameter: Name A, NominalValue 4+3i, Radius 1 
  

You can visualize the uncertain complex parameter by sampling and plotting the data.

• sa = usample(A,400); 
  w = linspace(0,2*pi,200); 
  circ = sin(w) + j*cos(w); 
  rc = real(A.NominalValue+circ); 
  ic = imag(A.NominalValue+circ); 
  plot(real(sa(:)),imag(sa(:)),'o',rc,ic,'k-') 
  xlim([2.5 5.5]) 
  ylim([1.5 4.5]) 
  axis equal
  
  
  

See Also
get         Gets object properties

umat        Creates an uncertain matrix object

ucomplexm   Creates an uncertain complex matrix

ultidyn     Creates an uncertain LTI dynamic object

ureal       Creates an uncertain real parameter

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