> Hi,
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>
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> I'm trying to implement a blocked QR algorithm, using the code from
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> HouseholderQR.
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> I'm using the algorithm used in lapack routine dgeqrf : first I make the
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> reduction of a panel of the input matrix, then I build the "T" triangular
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> factor in H=I-VT'V' that defines the blocked householder transformation,
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> then I apply this transformation to the trailing submatrix by a left
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> multiplication. Then I iterate the process.
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>
>
> I think that the current implemantation of householderQR does not comply
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> with lapack routine. The coefficients in hCoeffs() does actually not have
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> the same meaning than the one in the TAU vector found in dgeqrf. When
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> applying dlarft and dlarfb with hCoeffs to a partially reduced matrix, I
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> end with mostly different results than the one furnished by a complete
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> eigen householder decomposition (strangly the first row is correct).
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>
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> I suspect that the applyhousolderfrom the left use the coefficient in a
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> different war than dlarf in lapack does.
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>
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> Is there some doc on how hcoeffs from eigen and tau from lapack are
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> related ?
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>
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> Thanks, Vincent
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>
>