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20.1.6.1 Sparse Functions

Many of the internal functions of Octave, such as diag, cannot accept sparse matrices as an input directly. The sparse implementation uses the dispatch function to overload these functions with equivalent functions that work with sparse matrices. The sparse matrix version of any function can be also used explicitly calling its function name.

The table below lists all of the sparse functions of Octave. The names of the sparse forms of the functions are typically the same as the general versions with a sp prefix. In the table below, and the rest of this chapter the sparse versions of the function names are used.

Generate sparse matrices:

spalloc, spdiags, speye, sprand, sprandn, sprandsym

Sparse matrix conversion:

full, sparse, spconvert

Manipulate sparse matrices

issparse, nnz, nonzeros, nzmax, spfun, spones, spy

Graph Theory:

etree, etreeplot, gplot, treeplot

Sparse matrix reordering:

amd, ccolamd, colamd, colperm, csymamd, dmperm, symamd, randperm, symrcm

Linear algebra:

matrix_type, normest, condest, sprank spaugment

Iterative techniques:

luinc, pcg, pcr

Miscellaneous:

spparms, symbfact, spstats

Note that all of the standard Octave math functions that take a single argument, such as abs, etc can accept sparse matrices.