# Notation: $\operatorname{diag}(v,v)$ for a matrix?

What does the following notation for a matrix mean: $$\operatorname{diag}(v,v)$$ (to add context, this is written to be the vacuum value of the Higgs matrix).

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This might stand for $\begin{pmatrix}v & 0 \\ 0 & v\end{pmatrix}$. I'm not familiar with the context, so I can't say for sure. –  Dylan Moreland Jan 5 '12 at 3:25
Where did you find this notation? Is $v$ a number or a vector? –  Srivatsan Jan 5 '12 at 3:25
I'll note that I've seen $\mathrm{diag}$ used for both diagonal and block diagonal matrices. Saying where you saw this would help a great deal... –  Ｊ. Ｍ. Jan 5 '12 at 3:41
I have printed notes from previous years. On searching google books with the context, I found it used here –  kuch nahi Jan 5 '12 at 13:19

## migrated from physics.stackexchange.comJan 5 '12 at 3:22

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Usually, $diag(\lambda_1,\ldots,\lambda_n)$ denotes the n-dimensional matrix with those specific entries along the diagonal.
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