[Numpy-discussion] Should cholesky return upper or lower triangular matrix? (original) (raw)

Robert Kern robert.kern at gmail.com
Tue Jun 27 23🔞04 EDT 2006


Keith Goodman wrote:

Isn't the Cholesky decomposition by convention an upper triangular matrix? I noticed, by porting Octave code, that linalg.cholesky returns the lower triangular matrix.

References: http://mathworld.wolfram.com/CholeskyDecomposition.html http://www.mathworks.com/access/helpdesk/help/techdoc/ref/chol.html

Lower: http://en.wikipedia.org/wiki/Cholesky_decomposition http://www.math-linux.com/spip.php?article43 http://planetmath.org/?op=getobj&from=objects&id=1287 http://rkb.home.cern.ch/rkb/AN16pp/node33.html#SECTION000330000000000000000 http://www.riskglossary.com/link/cholesky_factorization.htm http://www.library.cornell.edu/nr/bookcpdf/c2-9.pdf

If anything, the convention appears to be lower-triangular.

-- Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth." -- Umberto Eco



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