Answer:
We want the ith row of the new matrix SijA to be the old jth row of A, so we need the ith row of Sij to extract the jth entry of column of A.
This mean the ith row of Sij must have a 1 in the jth entry and 0's everywhere else.
Similarly, the jth row of Sij must have a 1 in the ith entry and 0's everywhere else.
in the piecewise notation this is
(Sij)kl ={1 if k=i and l=j, 1 if k=k and l=i; 1 if k=l but k#i,j, 0 otherwise
Step-by-step explanation:
