rowcomp(1)

NAME
rowcomp - row compression, range

CALLING SEQUENCE
[W,rk]=rowcomp(A, flag, tol)

PARAMETERS

A   : real or complex matrix

flag
    : character string

tol : real number

W   : square non-singular matrix (change of basis)

rk  : integer (rank of A)

DESCRIPTION
Row compression of A. Ac = W*A is a row compressed matrix: i.e. Ac=[Af;0] with Af full row rank.

flag and tol are optional parameters: flag='qr' or 'svd' (default 'svd').

tol is a tolerance parameter (of order %eps as default value).

The rk first columns of W' span the range of A.

The rk first (top) rows of W span the row range of A.

Remark
A non zero vector x belongs to range(A) iff W*x is row compressed in accordance with Ac i.e the norm of its last components is small w.r.t its first components.

SEE ALSO
colcomp, fullrf, fullrfk

AUTHOR
F. D.