In
linear algebra, the
main diagonal of a
square matrix is the diagonal which runs from the top left corner to the bottom right corner. For example, the following matrix has 1s down its main diagonal:
- <math>\begin{bmatrix}
1 & 0 & 0\\
0 & 1 & 0\\
0 & 0 & 1\end{bmatrix}</math>
A matrix like the above in which only the elements of the main diagonal are non-zero is called a diagonal matrix. The sum of the entries on the main diagonal of a matrix is known as the trace of that matrix.
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