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