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replace custom rank one update in LU by an expression

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This commit is contained in:
Gael Guennebaud 2009-08-08 00:01:43 +02:00
parent d1dc088ef0
commit f5e1c896c7
1 changed files with 2 additions and 10 deletions
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12
Eigen/src/LU/LU.h
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@ -434,16 +434,8 @@ void LU<MatrixType>::compute(const MatrixType& matrix)
}
if(k<rows-1)
m_lu.col(k).end(rows-k-1) /= m_lu.coeff(k,k);
if(k<size-1) {
/* I know it's tempting to replace this for loop by a single matrix product. But actually there's no reason why it
* should be faster because it's just an exterior vector product; and in practice this gives much slower code with
* GCC 4.2-4.4 (this is weird, would be interesting to investigate). On the other hand, it would be worth having a variant
* for row-major matrices, traversing in the other direction for better performance, with a meta selector to compile only
* one path
*/
for(int col = k + 1; col < cols; ++col)
m_lu.col(col).end(rows-k-1) -= m_lu.col(k).end(rows-k-1) * m_lu.coeff(k,col);
}
if(k<size-1)
m_lu.block(k+1,k+1,rows-k-1,cols-k-1) -= m_lu.col(k).end(rows-k-1) * m_lu.row(k).end(cols-k-1);
}
for(int k = 0; k < matrix.rows(); ++k) m_p.coeffRef(k) = k;