symmmd (MATLAB Functions)

MATLAB Function Reference

symmmd

Sparse symmetric minimum degree ordering

Syntax

```
p = symmmd(S)
```

Note symmmd is obsolete and will be removed from a future version of MATLAB. Use symamd instead.

Description

p = symmmd(S) returns a symmetric minimum degree ordering of S. For a symmetric positive definite matrix S, this is a permutation p such that S(p,p) tends to have a sparser Cholesky factor than S. Sometimes symmmd works well for symmetric indefinite matrices too.

Algorithm

The symmetric minimum degree algorithm is based on the column minimum degree algorithm. In fact, symmmd(A) just creates a nonzero structure K such that K'*K has the same nonzero structure as A and then calls the column minimum degree code for K.

See Also

colamd, colmmd, colperm, symamd, symrcm

References

[1] Gilbert, John R., Cleve Moler, and Robert Schreiber, "Sparse Matrices in MATLAB: Design and Implementation," SIAM Journal on Matrix Analysis and Applications 13, 1992, pp. 333-356.

symmlq symrcm