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2018-05-11 19:54:10 +0100 commented question span of a matrixspace

@tmonteil done!

2018-05-11 19:52:36 +0100 received badge  Editor (source)
2018-05-11 14:12:54 +0100 received badge  Student (source)
2018-05-11 10:28:32 +0100 asked a question span of a matrixspace

given a matrix subspace of sparse matrices over a ring Q

M=MatrixSpace(Q,1000,1000, sparse=True)

I need a way to define the subspace N of M given a list of matrices of M

I tried to turn matrices into lists and use the VectorSpace category, however my matrices are sparse matrices, and this takes very long

def lista(A):  #converts a matrix into a list
return A.list()

def coor(P): # for the determined base B, it gives the coordinate vector of a matrix P[0]
   V=VectorSpace(Q,2**(2*k), sparse=True) #I would like to work with MatrixSpace instead
   B=[] #this will be my basis
   for i in range(len(A)):
   W=W=V.span_of_basis(B) #I dont know if this function exists in MatrixSpace
   return p