schur.Matrix(x, vectors=T, rcond=F, threshold=0, tune=<see below>,
             workspace=<see below>)

x:

numeric or complex square Matrix inheriting from class "Matrix". Missing values (NAs) are not allowed.

vectors:

a logical value telling whether or not to compute the Schur vectors. The default is to compute them.

rcond:

either a logical value or a logical vector of length 2 telling whether or not to compute reciprocal condition numbers for the eigenvalues and Schur vectors, respectively, and return them as attributes. By default, neither is computed.

threshold:

a numeric value. A diagonal block associated with a particular eigenvalue will appear in the top left portion of the Schur decomposition if it is greater than or equal to threshold in magnitude. By default, threshold is zero, so that eigenvalues are unordered. Further ordering can be obtained by applying schurmod to an existing Schur decomposition.

tune:

a integer vector or list of named tuning parameters that may affect computational efficiency. The relevant parameters are NB, NBMIN, NX, NS, and MAXB, as described in .laenv. The default is to use the settings in .laenv, which are initialized in S-Plus but may be changed by the user.

workspace:

workspace provided to the underlying software. The default is to use the minimum allowed value. The optimal workspace for the problem (for the given tune specifications) is included as part of the output attributes.

 n <- 9
 A <- Matrix( rnorm(n*n,sd = 100), nrow = n, ncol = n)
 schur.A <- schur(A)                                 # schur factorization
 mod.eig <- Mod(attr( schur.A, "eigenvalues"))       # eigenvalue modulus
 schur.A <- schur(schur.A)                           # reordered factorization