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I have created this formula using mathptmx as font

\begin{equation}
   BER = Q\left(\sqrt{\dfrac{2E_{b}^{\text{RX}}}{N_{0}}}\right)
\end{equation}

getting the above result:

enter image description here

I'm not totally satisfied of the space before the right bracket. I would know if the syntax is correct and if it is not please suggest me some correction

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I'm more bothered by the huge visual gap after the left parenthesis... –  cgnieder Jan 13 '13 at 14:30
    
@cgnieder Me too but I don't know how to fix –  Mazzy Jan 13 '13 at 14:33
    
\left(\! would reduce that –  David Carlisle Jan 13 '13 at 16:09

3 Answers 3

up vote 6 down vote accepted

I'm not following you with the fraction; in this case I would prefer the slash notation and also the mleftright package that avoids the "spurious" space between "Q" and the parenthesis:

\documentclass{article}
\usepackage{amsmath}
\usepackage{newtxtext,newtxmath}
\usepackage{mleftright}
\begin{document}
\begin{equation}
   BER = Q\mleft(\sqrt{2E_{b}^{\textnormal{RX}}\Big/N_{0}}\,\mright)
\end{equation}
\end{document}

enter image description here

Here's the same with mathptmx instead of newtxmath

enter image description here

and in this case some corrections are needed:

\begin{equation}
   BER = Q\Bigl(\sqrt{2E_{b}^{\textnormal{RX}}\big/N_{0}}\,\Bigr)
\end{equation}

enter image description here

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@Manuel Yes, thanks. –  egreg Jan 13 '13 at 15:53

In the case of your equation, I'd say that there are three issues that should be addressed so that its form doesn't draw attention to itself for the wrong reasons, i.e., clumsy typography, rather than for the mathematics:

  • the lack of space between the right-hand end of the square root sign and the closing right parenthesis (the issue you identify in your question);

  • the excessive space between the opening left parenthesis and the square root sign's opener; and

  • a sense that the parentheses are too large and thus visually quite dominant, relative to what's inside the parentheses.

Incidentally, it's not necessary to use \dfrac for your equation; \frac works just fine. The following MWE addresses these issues:

enter image description here

\documentclass{article}
\usepackage{amsmath,mathptmx}
\newcommand\tb\textbackslash
\begin{document}\pagestyle{empty}
\begin{align*}
Q \left(  \sqrt{\frac{2E_b^{\text{RX}}}{N_0}}  \right)
&\quad \text{initial form} \\
Q \left(\!\sqrt{\frac{2E_b^{\text{RX}}}{N_0}}\,\right)
&\quad \text{\texttt{\tb left(\tb !} and 
  \texttt{\tb ,\tb right)}}\\
Q\Biggl(\!\!\sqrt{\frac{2E_b^{\text{RX}}}{N_0}}\,\Biggr)
&\quad \text{\texttt{\tb Biggl(\tb !\tb !} and 
  \texttt{\tb ,\tb Biggr)}}
\end{align*}
\end{document}

Separately, the mathptmx package is known to generate math expressions that can look a bit cramped. If you're interested in perfecting the appearance of your formulas some more, you may want to look into using the MathTime Professional II font package. It's not a free package, unfortunately; however, its "lite" subset is free. :-) The following MWE shows what I would consider to be an even better looking version of your equation:

enter image description here

\documentclass{article}
\usepackage{amsmath,times,mtpro2}
\newcommand\tb\textbackslash
\begin{document}\pagestyle{empty}
\begin{align*}
Q\Biggl(\!\sqrt{\frac{2E_b^{\text{RX}}}{N_0}}\,\Biggr)
&\quad \text{\texttt{\tb Biggl(\tb !} and 
  \texttt{\tb ,\tb Biggr)}}
\end{align*}
\end{document}
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Please always post complete documents showing all packages used, the \dfrac caught me out first time.

There is is mathinner spacing from the \left\right You can use fixed size delimiters \biggl or simpler (but with spacing that differs again) using {} to get mathord spacing,

But actually I misread your question, you ask about the right bracket, yes I agree the spacing is very tight with the default cm or mathptmx setting, just add \, to compensate:

enter image description here

\documentclass{article}
\usepackage{amsmath}
%\usepackage{mathptmx}

\begin{document}

\begin{equation}
   BER = Q\left(\sqrt{\dfrac{2E_{b}^{\text{RX}}}{N_{0}}}\right)
\end{equation}
\begin{equation}
   BER = Q{\left(\sqrt{\dfrac{2E_{b}^{\text{RX}}}{N_{0}}}\right)}
\end{equation}
\begin{equation}
   BER = Q{\left(\sqrt{\dfrac{2E_{b}^{\text{RX}}}{N_{0}}}\,\right)}
\end{equation}

\end{document}
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