Linear_algebra.Make_VectorSpaceSourceinclude Module_sig with type t = Field.tzeros r c is a matrix with r rows and c columns filled with zeros
row_add ~coeff i j m adds to the i-th row, the j-th row times coeff in m
row_mul coeff i m multiplies the i-th row by coeff in m
filter_cols f m removes the columns of m whose index does not satisfy f