# need help with definition

• April 3rd 2009, 04:01 PM
justin016
need help with definition
I am having trouble understanding the given definition

- A square matrix A=[aij] is upper triangular if and only if the ith row starts with at least i-1 zeros.

I know what upper triangular looks like but the above definition doesnt make any sense to me, and what do they mean by (i-1 zeros).

• April 3rd 2009, 04:50 PM
HallsofIvy
Quote:

Originally Posted by justin016
I am having trouble understanding the given definition

- A square matrix A=[aij] is upper triangular if and only if the ith row starts with at least i-1 zeros.

I know what upper triangular looks like but the above definition doesnt make any sense to me, and what do they mean by (i-1 zeros).

$\begin{bmatrix}x & x & x \\ 0 & x & x \\ 0 & 0 & x\end{bmatrix}$