Let A be an invertible n×n matrix and denote by ri(A,j) the vector with entries as in row i of A with columns from 1,...,j. We can obtain ri(A,j) in Sage as follows:
def givesubmatrix(A,i,j):
B=A[[i-1],[0..j-1]]
return(B)
I want to find the permutation p(M) of the set [1,...,n] (it seems set brackets dont work in this forum using latex? So I use [ and ] instead for the set brackets) defined by the condition: p(A,i):=min Is there an easy way to obtain this permutation?
I have already problems to define the subspace [{r_i(A,j),...,r_{i-1}(A,j)] }.