Robust Control Toolbox™

Log-log scale plot of frd objects

Syntax

• loglog(sys)
  loglog(sys,linetype)
  

Description

loglog is the same as plot, except a logarithmic (base 10) scale is used for both the X- and Y-axis.

The argument list consists of (many) x-data, y-data and line type triples. The x-data and y-data can be specified individually, as doubles, or jointly as an frd.

Example

Generate three frequency response objects, sys1g, sys2g and sys3g. Plot the magnitude of these transfer functions versus frequency on a log-log plot.

• omega = logspace(-2,2,40); 
  sys1 = tf(0.9,[.1 1]); 
  sys1g = frd(sys1,omega); 
  sys2 = tf(0.9,[1 1]); 
  sys2g = frd(sys2,omega); 
  sys3 = tf(0.9,[10 1]); 
  sys3g = frd(sys3,omega); 
  loglog(abs(sys1g),abs(sys2g),'r+',sys3g.Freq,...
  abs(sys3g.Resp(:)),'--');
  
  
  

See Also
plot        Plots on linear axis

semilogx    Plots semi-log scale plot

semilogy    Plots semi-log scale plot

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