Returns the approximate minimum degree permutation of a matrix. This permutation such that the Cholesky factorization of s
(
p,
p)
tends to be sparser than the Cholesky factorization of s itself.amd
is typically faster thansymamd
but serves a similar purpose.The optional parameter opts is a structure that controls the behavior of
amd
. The fields of these structure are
- opts.dense
- Determines what
amd
considers to be a dense row or column of the input matrix. Rows or columns with more thatmax(16, (dense * sqrt (
n)
entries, where n is the order of the matrix s, are igorned byamd
during the calculation of the permutation The value of dense must be a positive scalar and its default value is 10.0- opts.aggressive
- If this value is a non zero scalar, then
amd
performs agressive absorption. The default is not to perform agressive absorption.The author of the code itself is Timothy A. Davis (davis@cise.ufl.edu), University of Florida (see http://www.cise.ufl.edu/research/sparse/amd).