Scilab Function

evans - Evans root locus

Calling Sequence

evans(H [,kmax])

Parameters

Description

Gives the Evans root locus for a linear system in state-space or transfer form H(s) (syslin list). This is the locus of the roots of 1+k*H(s)=1+k*N(s)/D(s), in the complex plane. For a selected sample of gains k <= kmax, the imaginary part of the roots of D(s)+k*N(s) is plotted vs the real part.

To obtain the gain at a given point of the locus you can simply execute the following instruction : k=-1/real(horner(h,[1,%i]*locate(1))) and click the desired point on the root locus. If the coordinates of the selected point are in the real 2 x 1 vector P=locate(1) this k solves the equation k*N(w) + D(w) =0 with w=P(1)+%i*P(2)=[1,%i]*P.

Examples

See Also