Trace

Suppose $A=(a_{ij})_{n\times n}$ is an square matrix. Trace of $A$ is the sum of the diagonal entries.

\text{trace}(A)=\text{Tr}(A)=\sum_{i=1}^n{a_{ii}}

Trace is also equal to the sum of eigenvalues.

\text{trace}(A)=\sum{\lambda_i}\text{ where } \lambda_i \in \text{spectrum of } A

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September 29, 2026 1 min read

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