rank - rank

Calling Sequence

[i]=rank(X)

[i]=rank(X,tol)

Parameters

• X : real or complex matrix
• tol : nonnegative real number

Description

is the numerical rank of X i.e. the number of singular values of X that are larger than norm(size(X),'inf') * norm(X) * %eps.

rank(X,tol) is the number of singular values of X that are larger than tol.

Remark

Note that the default value of tol is proportional to norm(X). As a consequence

rank([1.d-80,0;0,1.d-80]) is 2 !.

Examples

rank([1.d-80,0;0,1.d-80])
rank([1,0;0,1.d-80])
 

See Also

svd  qr  rowcomp  colcomp  lu