is an option to NicholsPlot that specifies contours of constant magnitude and constant phase of the closed-loop system.


  • The following settings can be given:
  • Noneno contours drawn
    Automaticcontours chosen automatically
    {magnitude,phase}contours specified by magnitude and phase are drawn
  • The magnitude values are the absolute values.
  • The phase values are in radians.
  • The following settings can be given for magnitude and phase:
  • Noneno contours drawn
    Automaticcontours chosen automatically
    {c1,c2,}draw the contours ci
    {{c1,style1,r1},}contours with specified styles and regions
  • The default style of a magnitude contour is Dashed, and the default style of a phase contour is Dotted.
  • The setting ri specifies that a point should be included if ri[x,y,ci] yields True.
  • The default value of ri is Automatic.


open allclose all

Basic Examples  (1)

Show the closed-loop magnitude and phase contours:

Scope  (8)

Choose contours automatically:

Show specific magnitude and phase contours:

Use different contour styles:

Specify different regions:

Magnitude contours with specific dB values:

Specify contours with phase from -70 to 70 degrees in increments of 5:

The contours depend on the type of feedback:

A discrete-time system:

Applications  (1)

Estimate closed-loop magnitude and phase values at various frequencies:

Introduced in 2010