Difference between revisions of "Trace"

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== Properties ==
 
== Properties ==
  
Viewed as a function from <math>n \times n</math> matrices to the underlying [[field]] (frequently the [[real number]]s), the trace is a [[linear map]]: it is not difficult to verify that <math>\text{tr}(cA + B) = c\text{tr}(A) + \text{tr}(B)</math> for any <math>n \times n</math> matrices <math>A</math> and <math>B</math>.
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Viewed as a function from <math>n \times n</math> matrices to the underlying [[field]] (frequently the [[real number]]s), the trace is a [[linear map]]: it is not difficult to verify that <math>\text{tr}(cA + B) = c\, \text{tr}(A) + \text{tr}(B)</math> for any <math>n \times n</math> matrices <math>A</math> and <math>B</math> and any scalar <math>c</math>.
  
  

Latest revision as of 18:27, 2 March 2010

The trace of a square $n \times n$ matrix is the sum of the elements of the main diagonal of the matrix. For example, the trace of the matrix $M = \begin{pmatrix} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9\end{pmatrix}$ is $\text{tr}(M) = 1 + 5 + 9 = 15$.

Properties

Viewed as a function from $n \times n$ matrices to the underlying field (frequently the real numbers), the trace is a linear map: it is not difficult to verify that $\text{tr}(cA + B) = c\, \text{tr}(A) + \text{tr}(B)$ for any $n \times n$ matrices $A$ and $B$ and any scalar $c$.


See also

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