QR Decomposition of a Matrix

DESCRIPTION:
Computes the QR decomposition of a Matrix.

USAGE:
qr.Matrix(x, pivot=F, tune=<see below>, workspace=<see below>)

REQUIRED ARGUMENTS:
x:
numeric or complex matrix. Missing values (NAs) are not allowed.

OPTIONAL ARGUMENTS:
pivot:
a logical vector of length equal to the number of columns in x, indicating whether or not each column is free for pivoting. The parameter pivot can also be a single logical value, indicating either that all or no columns are free for pivoting. By default, no column pivoting is done.
tune:
a integer vector or list of named tuning parameters that may affect computational efficiency when no pivoting is done. The relevant parameters are the blocksize parameters NB, NBMIN, and NX as described in .laenv. This parameter has no effect when pivoting is allowed. The default is to use the settings in .laenv, which in S-Plus is initialized to use an unblocked algorithm (NB = 1), but may be changed by the user.
workspace:
workspace provided to the underlying software. The default is to use the optimum value according to tune. The optimal workspace for the problem (for the given tune specifications) is included as part of the output attributes.

VALUE:
The QR decomposition of x is returned as an object of class c("qr.Matrix", "decomp"). A copy of the call to qr.Matrix is included as an attribute.

DETAILS:
Based on the functions dgeqrf, dgeqpf, zgeqrf, and zgeqpf from LAPACK (Anderson et al. 1994). Parameters in tune may affect performance and workspace requirements, but the optimal settings are both machine and problem dependent. Users may want to experiment with tune (see Anderson et al., p. 72-74) to obtain improved performance.

REFERENCES:
Anderson, E., et al. (1994). LAPACK User's Guide, 2nd edition, SIAM, Philadelphia.

SEE ALSO:
qr.Matrix.object , facmul.qr.Matrix , expand.qr.Matrix , .laenv

EXAMPLES:
 A <- Matrix( rnorm(60), nrow = 12, ncol = 5)
 qr(A, pivot = T)                           # QR factorization of A