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.TH nlev 1 "April 1993" "Scilab Group" "Scilab Function"
.so ../sci.an
.SH NAME
nlev - Leverrier's algorithm
.SH CALLING SEQUENCE
.nf
[num,den]=nlev(A,z [,rmax])
.fi
.SH PARAMETERS
.TP 6
A
: real square matrix
.TP
z
: character string
.TP
rmax
: optional parameter (see \fVbdiag\fR)
.SH DESCRIPTION
.Vb [num,den]=nlev(A,z [,rmax])
computes:
.IG
.nf
(z*eye-A)^(-1)
.fi
.FI
.LA $ (z I -A)^{-1} $
by block diagonalization of A followed by Leverrier's algorithm
on each block.
.SH Remark
This algorithm is better than the usual leverrier algorithm
but still not perfect!
.SH EXAMPLE
.nf
A=rand(3,3);x=poly(0,'x');
[NUM,den]=nlev(A,'x')
clean(den-poly(A,'x'))
clean(NUM/den-inv(x*eye-A))
.fi
.SH SEE ALSO
coff, coffg, glever, ss2tf
.SH AUTHOR
F. D., S. S.
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