# But why are the two sets of absolute parentheses different sizes?

Silly question maybe - but why are the two sets of absolute different sizes?

Is there an easy way to set the size locally - or globally?

\documentclass{article}
\usepackage{amsmath}
\newcommand{\vect}[1]{\mathbf{\underline{#1}}}

\begin{document}

$I (\theta, \varphi) = \left | \vect{E}_{dir}^p(\theta, \varphi, r)_{\infty} + \vect{E}_{ref}^p(\theta, \varphi, r)_{\infty} \right |^2 + \left | \vect{E}_{dir}^s(\theta, \varphi, r)_{\infty} + \vect{E}_{dir}^s(\theta, \varphi, r)_{\infty} \right |^2$

\end{document}

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Welcome to TeX.sx!Can you wrap your code with a simple MWE with your definition of \vect or the package loading it? – percusse Mar 14 '13 at 0:40
I don't see what "absolute different sizes" are you refering to.. I get this result (defined \vect as \vec) – JLDiaz Mar 14 '13 at 0:43
Also, you should use \text{dir}, \text{ref} instead of dir and ref. Note the weird kerning you got in "ref". In math mode a sequence of letters is not considered a word, but instead a product of single-char named variables, hence the odd spacing. – JLDiaz Mar 14 '13 at 0:46
thanks for the advice. As for your questions - I redefined the 'vect' command - since I wasn't 100% sure what look I would go for in general (in terms of bold\underline etc - so I figured that if i defined it right at the beginning it would sort it out. – JPH Mar 14 '13 at 1:34
I added the newcommand...BTW what does MWE stand for? – JPH Mar 14 '13 at 1:38

You get different sizes because of the f in the subscript.

There's no need of \left and \right here; in other words, they are not the best choice here.

I propose two versions, one with normal sized bars (which I prefer), one with slightly bigger ones.

\documentclass{article}
\usepackage{amsmath}
\newcommand{\vect}[1]{\mathbf{#1}}
\newcommand{\tsub}[1]{\textnormal{#1}}
\begin{document}
$I (\theta, \varphi) = \lvert \vect{E}_\tsub{dir}^p(\theta, \varphi, r)_{\infty} + \vect{E}_\tsub{ref}^p(\theta, \varphi, r)_{\infty} \rvert^2 + \lvert \vect{E}_\tsub{dir}^s(\theta, \varphi, r)_{\infty} + \vect{E}_\tsub{dir}^s(\theta, \varphi, r)_{\infty} \rvert^2$

$I (\theta, \varphi) = \bigl\lvert \vect{E}_\tsub{dir}^p(\theta, \varphi, r)_{\infty} + \vect{E}_\tsub{ref}^p(\theta, \varphi, r)_{\infty} \bigr\rvert^2 + \bigl\lvert \vect{E}_\tsub{dir}^s(\theta, \varphi, r)_{\infty} + \vect{E}_\tsub{dir}^s(\theta, \varphi, r)_{\infty} \bigr\rvert^2$
\end{document}


Notice how I realized the textual subscripts; this kind of subscript should go in upright type and \textnormal ensures it.

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