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.TH sparse 1 "January 1995" "Scilab Group" "Scilab Function"
.so ../sci.an
.SH NAME
sparse - sparse matrix definition
.SH CALLING SEQUENCE
.nf
sp=sparse(X)
sp=sparse(ij,v [,mn])
.fi
.SH PARAMETERS
.TP
X
: real or complex full (or sparse) matrix
.TP
ij
: two columns integer matrix (indices of non-zeros entries)
.TP
mn
: integer vector with two entries (row-dimension, column-dimension)
.TP
sp
: sparse matrix
.SH DESCRIPTION
\fVsparse\fR is used to build a sparse matrix. Only non-zero entries
are stored.
.LP
\fVsp = sparse(X)\fR converts a full matrix to sparse form by
squeezing out any zero elements. (If \fVX\fR is already sparse
\fVsp\fR is \fVX\fR).
.LP
\fVsp=sparse(ij,v [,mn])\fR builds an \fVmn(1)\fR-by-\fVmn(2)\fR
sparse matrix with \fVsp(ij(k,1),ij(k,2))=v(k)\fR.
\fVij\fR and \fVv\fR must have the same column dimension.
If optional \fVmn\fR parameter is not given the \fVsp\fR
matrix dimensions are the max value of \fVij(:,1)\fR and \fVij(:,2)\fR
respectively.
.LP
Operations (concatenation, addition, etc,) with sparse matrices are
made using the same syntax as for full matrices.
.LP
Elementary functions are also available (\fVabs,maxi,sum,diag,...\fR)
for sparse matrices.
.LP
Mixed operations (full-sparse) are allowed. Results are full or sparse
depending on the operations.
.SH EXAMPLE
.nf
sp=sparse([1,2;4,5;3,10],[1,2,3])
size(sp)
x=rand(2,2);abs(x)-full(abs(sparse(x)))
.fi
.SH SEE ALSO
full, spget, sprand, speye, lufact
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