speye

Sparse identity matrix.

Syntax

S = speye(n)
S = speye(m, n)

Description

Returns a sparse identity matrix — n × n square or m × n rectangular with ones on the main diagonal and zeros elsewhere. Equivalent to sparse(eye(...)) but builds in sparse storage from the start (much cheaper for large n).

Examples

speye(1000)              % 1000×1000 sparse identity
speye(3, 5)              % 3×5 with ones on the main diagonal

See also

• eye — Identity matrix.
• sparse — Create a sparse matrix.
• spones — Replace non-zero entries with 1s.