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rowshuff Scilab Group Scilab Function rowshuff
NAME
rowshuff - shuffle algorithm
CALLING SEQUENCE
[Ws,Fs1]=rowshuff(Fs, [alfa])
PARAMETERS
Fs : square real pencil Fs = s*E-A
Ws : polynomial matrix
Fs1 : square real pencil F1s = s*E1 -A1 with E1 non-singular
alfa : real number (alfa = 0 is the default value)
DESCRIPTION
Shuffle algorithm: Given the pencil Fs=s*E-A , returns Ws=W(s) (square
polynomial matrix) such that:
Fs1 = s*E1-A1 = W(s)*(s*E-A) is a pencil with non singular E1 matrix.
This is possible iff the pencil Fs = s*E-A is regular (i.e. invertible).
The degree of Ws is equal to the index of the pencil.
The poles at infinity of Fs are put to alfa and the zeros of Ws are at
alfa.
Note that (s*E-A)^-1 = (s*E1-A1)^-1 * W(s) = (W(s)*(s*E-A))^-1 *W(s)
EXAMPLE
F=randpencil([],[2],[1,2,3],[]);
F=rand(5,5)*F*rand(5,5); // 5 x 5 regular pencil with 3 evals at 1,2,3
[Ws,F1]=rowshuff(F,-1);
[E1,A1]=pen2ea(F1);
svd(E1) //E1 non singular
roots(det(Ws))
clean(inv(F)-inv(F1)*Ws,1.d-7)
SEE ALSO
pencan, glever, penlaur
AUTHOR
F. D.
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