In reviewing recent knowledge of linear algebra, sudden inspiration, if the matrix of the favorite people tell the truth, I feel a lot of fun (provided that the person to be able to understand)
So thought about elementary transformation matrix, elementary transformation carried out by the 4-order unit matrix, let 521,1314 appear in the matrix
Small routine: After she finished this question, if the name is three words put her name to fill three places above the lower triangle, if the word is to fill in the lower triangle on the diagonal.