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.TH st_ility 1 "April 1993" "Scilab Group" "Scilab Function"
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st_ility - stabilizability test
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[ns, [nc, [,U [,Slo] ]]]=st_ility(Sl [,tol])
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: \fVsyslin\fR list (linear system)
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: integer (dimension of stabilizable subspace)
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: integer (dimension of controllable subspace \fVnc <= ns\fR)
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: basis such that its \fVns\fR (resp. \fVnc\fR) first components span
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the stabilizable (resp. controllable) subspace
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: a linear system (\fVsyslin\fR list)
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: threshold for controllability detection (see contr)
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\fV Slo=( U'*A*U, U'*B, C*U, D, U'*x0 )\fR (\fVsyslin\fR list)
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displays the stabilizable form of \fVSl\fR. Stabilizability means
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\fVns=nx\fR (dim. of \fVA\fR matrix).
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U'*A*U = [0,*,*] U'*B = [0]
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where \fV (A11,B1) \fR (dim(A11)= \fVnc\fR) is controllable and \fVA22\fR
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(dim(A22)=\fVns-nc\fR) is stable.
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"Stable" means real part of eigenvalues negative for a continuous
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linear system, and magnitude of eigenvalues lower than one for a
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discrete-time system (as defined by \fVsyslin\fR).
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A=diag([0.9,-2,3]);B=[0;0;1];Sl=syslin('c',A,B,[]);
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[ns,nc,U]=st_ility(Sl);
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[ns,nc,U]=st_ility(syslin('d',A,B,[]));
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dt_ility, contr, stabil, ssrand