Description of qrank

qrank

PURPOSE

QRANK - Quick matrix rank estimation.

SYNOPSIS

function r = qrank(A)

DESCRIPTION

 QRANK - Quick matrix rank estimation.

  r = qrank(A)

 Provides an estimate of rank(A) based on the QR decomposition of
 A. Faster than Matlab's RANK which relies on the SVD.

CROSS-REFERENCE INFORMATION

This function calls:

This function is called by:

• iscoplanar ISCOPLANAR - Test for coplanar controls.

SOURCE CODE

0001 function r = qrank(A)
0002   
0003 % QRANK - Quick matrix rank estimation.
0004 %
0005 %  r = qrank(A)
0006 %
0007 % Provides an estimate of rank(A) based on the QR decomposition of
0008 % A. Faster than Matlab's RANK which relies on the SVD.
0009   
0010 % Compute QR decomposition.
0011   [Q1,R1,E] = qr(A',0);
0012   % The tolerance is 10 x tolerance used in \. See qr documentation.
0013   tol = max(size(A))*10*eps*abs(R1(1,1));
0014   % Compute numerical rank.
0015   r = sum(abs(diag(R1))>tol);

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