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Aide Scilab >> Algèbre Lineaire > spaninter


subspace intersection

Calling Sequence

[X,dim]=spaninter(A,B [,tol])


A, B

two real or complex matrices with equal number of rows


orthogonal or unitary square matrix


integer, dimension of subspace range(A) inter range(B)


computes the intersection of range(A) and range(B).

The first dim columns of X span this intersection i.e. X(:,1:dim) is an orthogonal basis for

range(A) inter range(B)

In the X basis A and B are respectively represented by:

X'*A and X'*B.

tol is a threshold (sqrt(%eps) is the default value).


A=rand(5,3)*rand(3,4);     // A is 5 x 4, rank=3
X1=X(:,1:dim);    //The intersection
svd(A),svd([X1,A])   // X1 in span(A)
svd(B),svd([B,X1])   // X1 in span(B)

See Also

  • spanplus — sum of subspaces
  • spantwo — sum and intersection of subspaces


F. D.; ;

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Last updated:
Wed Oct 05 12:10:40 CEST 2011