Definition:Trace (Linear Algebra)/Matrix/Einstein Summation Convention

Definition

Let $A = \sqbrk {a_{ij} }_{1 \mathop \le i, j \mathop \le n}$ be a matrix.

The trace of $A$, using the Einstein summation convention, is:

$\map \tr A = a_{ii}$

Sources

• 1980: A.J.M. Spencer: Continuum Mechanics ... (previous) ... (next): $2.2$: The summation convention