rank¶

rank

Calling Sequence¶

[i]=rank(X)
[i]=rank(X,tol)

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

rank(X) 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.

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 !.

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