2-norm estimate
nrm = normest(S)
nrm = normest(S,tol)
[nrm,count] = normest(...)
This function is intended primarily for sparse matrices, although it works correctly and may be useful for large, full matrices as well.
nrm = normest(S) returns
an estimate of the 2-norm of the matrix S.
nrm = normest(S,tol) uses
relative error tol instead of the default tolerance 1.e-6.
The value of tol determines when the estimate is
considered acceptable.
[nrm,count] = normest(...) returns
an estimate of the 2-norm and also gives the number of power iterations
used.
The power iteration involves repeated multiplication by the
matrix S and its transpose, S'.
The iteration is carried out until two successive estimates agree
to within the specified relative tolerance.