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  • Committer: Bazaar Package Importer
  • Author(s): Torsten Werner
  • Date: 2002-03-21 16:57:43 UTC
  • Revision ID: james.westby@ubuntu.com-20020321165743-e9mv12c1tb1plztg
Tags: upstream-2.6
Import upstream version 2.6

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man/linear/rcond.man
 
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.TH rcond 1 "April 1993" "Scilab Group" "Scilab Function"
 
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.so ../sci.an
 
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.SH NAME
 
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rcond -  inverse condition number
 
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.SH CALLING SEQUENCE
 
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.nf
 
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rcond(X) 
 
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.fi
 
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.SH PARAMETERS
 
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.TP
 
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X
 
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: real or complex square matrix
 
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.SH DESCRIPTION
 
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.Vb rcond(X)
 
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is an estimate for the reciprocal of the
 
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condition of \fVX\fR in the 1-norm.
 
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.LP
 
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If \fVX\fR is well conditioned, \fVrcond(X)\fR is close to 1.
 
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If not, \fVrcond(X)\fR is close to 0.
 
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.LP
 
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.Vb [r,z]=rcond(X)  
 
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sets \fVr\fR to \fVrcond(X)\fR and returns \fVz\fR such that
 
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.LP
 
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.Vb norm(X*z,1) = r*norm(X,1)*norm(z,1) 
 
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Thus, if \fVrcond\fR is small \fVz\fR is a vector in the kernel.
 
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.SH EXAMPLE
 
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.nf
 
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A=diag([1:10]);
 
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rcond(A)
 
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A(1,1)=0.000001;
 
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rcond(A)
 
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.fi
 
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.SH SEE ALSO
 
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svd, cond, inv
 
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