Subspace generated by the rows of a matrix : rowspace

### 2.43.15 Subspace generated by the rows of a matrix : `rowspace`

`rowspace` takes as argument the matrix A of an linear application f with respect to the canonical basis.
`rowspace` returns a list of vectors that is a basis of the subspace generated by the rows of A.
`rowspace` may have a variable name as second argument where `Xcas` will store the dimension of the subspace generated by the rows of A.
Input :

`rowspace([[1,1,2],[2,1,3],[3,1,4]])`

Output :

`[[-1,0,-1],[0,-1,-1]]`

Input :

`rowspace([[1,1,2],[2,1,3],[3,1,4]],dimension)`

Output :

`[[-1,0,-1],[0,-1,-1]]`

Then input:

`dimension`

Output :

`2`