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C++ API

: p = amd (S)
: p = amd (S, opts)

Return the approximate minimum degree permutation of a matrix.

This is a 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 than symamd but serves a similar purpose.

The optional parameter opts is a structure that controls the behavior of amd. The fields of the structure are

opts.dense

Determines what amd considers to be a dense row or column of the input matrix. Rows or columns with more than max (16, (dense * sqrt (n))) entries, where n is the order of the matrix S, are ignored by amd during the calculation of the permutation. The value of dense must be a positive scalar and the default value is 10.0

opts.aggressive

If this value is a nonzero scalar, then amd performs aggressive absorption. The default is not to perform aggressive 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).

See also: symamd, colamd.

Package: octave