# I need to reduce the fontsize of only one equation/formula because it's too long

$$\left| Y(j \omega) \right| = \sqrt{\frac{\omega^2 \left( C\ped{DC} + C\ped{eq} \right)^2 + \omega^4 \left[ \left( R\ped{eq} C\ped{eq} C\ped{DC} \right)^2 - 2 \left( C\ped{DC} + C\ped{eq} \right) \left( L\ped{eq} C\ped{eq} C\ped{DC} \right) \right] + \omega^6 \left( L\ped{eq} C\ped{eq} C\ped{DC} \right)^2}{1 + \omega^2 \left[ \left( R\ped{eq} C\ped{eq} \right)^2 - 2 L\ped{eq} C\ped{eq} \right] + \omega^4 \left( L\ped{eq} C\ped{eq} \right)^2}}. \label{eq:cmut:abs_y_w_eq}$$


Hi. This is an equation I have to write. It's too long. (I cannot show you the results because I don't have enough reputation points to post images). How can I reduce the fontsize of the equation (without reducing the fontsize of the number of the reference)? Any suggestion to solve this problem? Thank you.

• Could you provide a MWE? From the document class declaration and packages loaded through to the end of the document? For example, if I try to compile your snippet, I get a compilation error with \ped. I'm not sure whether that's a user defined macro or something else. Either way, I'm unfamiliar with it. – A.Ellett Feb 22 '13 at 15:58
• Welcome to TeX.sx! Reducing the size won't help; assuming the standard settings for 10pt article on A4 paper, even at \scriptsize the formula is too wide. With \tiny it is not overfull, but it becomes unreadable. – egreg Feb 22 '13 at 16:07
• Please, bear in mind that \ped is not a standard command, but is only provided by the italian option to babel. So you see the necessity for a minimal working example (MWE) – egreg Feb 22 '13 at 16:18

Reducing the size won't help; assuming the standard settings for 10pt article on A4 paper, even at \scriptsize the formula is too wide. With \tiny it is not overfull, but it becomes unreadable.

A possibility is to avoid the radical, squaring the left hand side, and using multlined from the mathtools package for the numerator:

\documentclass[a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc} % or other encoding
\usepackage[italian]{babel}

\usepackage{amsmath,mathtools}

\begin{document}
$$\lvert Y(j \omega) \rvert^2 = \frac{ \begin{multlined}[b] \omega^2 ( C\ped{DC} + C\ped{eq} )^2 \\ \qquad{} +\omega^4 [ ( R\ped{eq} C\ped{eq} C\ped{DC} )^2 - 2 (C\ped{DC} + C\ped{eq} ) ( L\ped{eq} C\ped{eq} C\ped{DC} ) ] \qquad\\ {} + \omega^6 ( L\ped{eq} C\ped{eq} C\ped{DC} )^2 \end{multlined} } { 1 + \omega^2 [ ( R\ped{eq} C\ped{eq} )^2 - 2 L\ped{eq} C\ped{eq} ] + \omega^4 ( L\ped{eq} C\ped{eq} )^2 }. \label{eq:cmut:abs_y_w_eq}$$
\end{document}


The two \qquad commands are just to widen the middle row which shouldn't be broken, but becomes the longest, spoiling the alignment.

Don't overuse \left and \right; in this formula none of them is needed.

A different strategy might be to use symbolic names for the coefficients: with the same preamble as before (but mathtools is not necessary), you can write

\begin{align}
\lvert Y(j \omega) \rvert &=
\sqrt{
\frac{X_2 \omega^2 + X_4 \omega^4 + X_6 \omega^6}
{1 + Y_2 \omega^2 + Y_4 \omega^4}
},\\[2ex]
%%%
X_2 &= ( C\ped{DC} + C\ped{eq} )^2
\notag\\
X_4 &= ( R\ped{eq} C\ped{eq} C\ped{DC} )^2 -
2 (C\ped{DC} + C\ped{eq} ) ( L\ped{eq} C\ped{eq} C\ped{DC} )
\notag\\
X_6 &= ( L\ped{eq} C\ped{eq} C\ped{DC} )^2
\notag\\
Y_2 &= ( R\ped{eq} C\ped{eq} )^2 - 2 L\ped{eq} C\ped{eq}
\notag\\
Y_4 &= ( L\ped{eq} C\ped{eq} )^2
\notag
\end{align}


and get the following result

• The OP's readers will thank you if he adopts your suggestion to name the coefficients. – Ethan Bolker Feb 22 '13 at 16:44