spanplus - Sum of subspaces (original) (raw)

Scilab 5.3.3

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See the recommended documentation of this function

Scilab help >> Linear Algebra > spanplus

Calling Sequence

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

Arguments

A, B

two real or complex matrices with equal number of rows

X

orthogonal or unitary square matrix

dim, dima

integers, dimension of subspaces

tol

nonnegative real number

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);
B=[A(:,1),rand(6,2)]
rand(3,3);
[X,dim,dimA]=spanplus(A,B); dimA dim

See Also