Scilab Function
Last update : 18/05/2014

spanplus - sum of subspaces

Calling Sequence

[X,dim,dima]=spanplus(A,B[,tol])

Parameters

Description

computes a basis X such that:

the first dima columns of X span Range(A) and the following (dim-dima) columns make a basis of A+B relative to A.

The dim first columns of X make a basis for A+B.

One has the following canonical form for [A,B]:


         [*,*]    (dima rows)
X'*[A,B]=[0,*]    (dim-dima rows)
         [0,0]    
   
    

tol is an optional argument (see function code).

Examples


A=rand(6,2)*rand(2,5);      // rank(A)=2
B=[A(:,1),rand(6,2)]*rand(3,3);   //two additional independent vectors
[X,dim,dimA]=spanplus(A,B);
dimA
dim
 
  

See Also

spaninter,  im_inv,  spantwo,  

Author

F. D.; ;