### How to get the left matrix that was used to obtain reduced row echelon form?

Hi all.

I have a matrix A and would like to determine a matrix E such that E*A = R, where R is the reduced row echelon form of the matrix A. I just know the command R = A.rref(). But I don't know how to get E (my stupid solution is to compute the inverse of the pivot columns of A ...). Is there e.g. an argument such that A.rref() also outputs E?

Thanks a lot,
Julian