colcomp

Arguments

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

Column compression of A: Ac = A*W is column compressed i.e

Ac=[0,Af] with Af full column rank, rank(Af) = rank(A) = rk.

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

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

The ma-rk first columns of W span the kernel of A when size(A)=(na,ma)

Examples

A=rand(5,2)*rand(2,5);
[X,r]=colcomp(A);
norm(A*X(:,1:$-r),1)

See Also

• rowcomp — row compression, range
• fullrf — full rank factorization
• fullrfk — full rank factorization of A^k
• kernel — kernel, nullspace