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Re: matrix_type problems


From: Vic Norton
Subject: Re: matrix_type problems
Date: Mon, 4 Dec 2006 09:46:54 -0500

On 12/4/06, at 6:16 PM +0100, David Bateman wrote:
> You don't have to force the recognition. The matrix will be recognized
> as upper triangular.

Thanks David! You've answered all my questions. I extremely pleased that Octave 
now takes advantage of triangular structure!

I guess I won't use the matric_type function at all. I am now using the tests
   if QQ_check
      if norm(QQ(:, 1:nJ)' * QQ(:, 1:nJ) - eye(nJ), 1) > rows(QQ) * eps
         error("the columns of Q are not orthonormal");
      endif
   endif
   if RR_check
      RR_requirements = !sum(diag(RR(1:nJ, 1:nJ)) == 0);
      for i = 2:nJ
         RR_requirements = RR_requirements && !sum(RR(i, 1:i-1) != 0);
      endfor
      if !RR_requirements
         error("R is singular or is not upper triangular");
      endif
   endif
to check my QRs. I don't care about speed here. I'll set
   QQ_check = false;  RR_check = false;
in applications.

Regards,

Vic



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