Campus Livre
spalloc
Creates an empty sparse matrix with room reserved for nonzeros.
Category: Mathematics > Sparse Matrices
Syntax
S = spalloc(m, n, nzmax)Returns an m-by-n all-zero sparse matrix with space for nzmax nonzeros.
Description
spalloc(m, n, nzmax) is sparse(m, n) with a hint about how many entries will be filled in later. When a matrix is built by assigning elements one at a time, reserving the space avoids repeated reallocation. The matrix is still all zeros until you assign to it.
Input arguments
m, n- Number of rows and columns.
nzmax- Number of nonzeros to reserve space for.
Output arguments
S- Sparse matrix with
nnz(S) = 0.
Example
Reserve, then fill
S = spalloc(3, 3, 4);
nnz(S)
S(1, 1) = 5;
S(3, 2) = 7;
nnz(S)
full(S)Output
ans = 0
ans = 2
ans = 3×3
5 0 0
0 0 0
0 7 0