3

I need to scale down my math equation, I looked on the forum and it only addresses one part of my problem, splitting the equation into two lines, but the first line still exceeds the textwidth. I dont think it would look good if I split the upper part of the equation since it loses the flow. Thanks for the help.

issue

\documentclass[a4paper, 12pt]{report}
\usepackage[utf8]{inputenc}
\usepackage{graphicx}
\usepackage{url}
\usepackage{amsmath}

\begin{document}
\begin{equation}
\label{eq:K}
\begin{split}
A = \Bigg\{\varepsilon_G b ~+ ~\dfrac{\varepsilon_{HG} bK[H]_t}{1+0.5\big(-(1-K[G]_t +K[H]_t) + \sqrt{(1-K[G]_t +K[H]_t)^2 + 4K[G]_t}\big)}\Bigg\}  \\  \times \dfrac{-(1-K[G]_t + K[H]_t) + \sqrt{(1-K[G]_t + K[H]_t)^2 + 4K[G]_t}}{2K}
\end{split}
\end{equation}
\end{document}
1
  • Your terms will shrink if you use a shorthand for 1-K[G]_t +K[H]_t. Use \bigl and \bigr (and similar), not \big. – egreg Jul 10 '15 at 23:11
1

I propose three solutions: with the \splitfrac command (from mathtools) or reducing fontsize to \footnotesize, or using \mfrac from nccmath: it is a medium-sized fraction, about 80% of displaystyle:

\documentclass[a4paper, 12pt]{report}
\usepackage[utf8]{inputenc}
\usepackage[showframe]{geometry}
\usepackage{mathtools}
\usepackage{nccmath} 

\begin{document}
\mbox{}
\begin{equation}
  \label{eq:K}
  \begin{split}
    A & = \left\{\varepsilon_G b +\dfrac{\varepsilon_{HG} bK[H]_t}{\splitfrac{1+0.5\big(-(1-K[G]_t +K[H]_t)}{ + \sqrt{(1-K[G]_t +K[H]_t)^2 + 4K[G]_t}\big)}}\right\} \\[1ex] & \quad\times \dfrac{-(1-K[G]_t + K[H]_t) + \sqrt{(1-K[G]_t + K[H]_t)^2 + 4K[G]_t}}{2K}
    \end{split}
  \end{equation}

{\footnotesize \begin{equation}
  \label{eq:K}
  \begin{split}
    A & = \left\{\varepsilon_G b +\dfrac{\varepsilon_{HG} bK[H]_t}{1+0.5\big(-(1-K[G]_t +K[H]_t) + \sqrt{(1-K[G]_t +K[H]_t)^2 + 4K[G]_t}\big)}\right\} \\[1ex] & \quad\times \dfrac{-(1-K[G]_t + K[H]_t) + \sqrt{(1-K[G]_t + K[H]_t)^2 + 4K[G]_t}}{2K}
    \end{split}
  \end{equation}
}

\begin{equation}
  \label{eq:K}
  \begin{split}
    A & = \left\{\varepsilon_G b +\mfrac{\varepsilon_{HG} bK[H]_t}{1+0.5\big(-(1-K[G]_t +K[H]_t) + \sqrt{(1-K[G]_t +K[H]_t)^2 + 4K[G]_t}\big)}\right\} \\[1ex] & \quad\times \mfrac{-(1-K[G]_t + K[H]_t) + \sqrt{(1-K[G]_t + K[H]_t)^2 + 4K[G]_t}}{2K}
    \end{split}
  \end{equation}
\end{document} 

enter image description here

2

You have no real hope of shrinking that big fraction, unless you use a shorthand:

\documentclass[a4paper, 12pt]{report}
\usepackage[utf8]{inputenc}
\usepackage{graphicx}
\usepackage{url}
\usepackage{amsmath}

\begin{document}
\begin{equation}
\label{eq:K}
\begin{split}
A = \Biggl\{\varepsilon_G b 
  &+ \dfrac{\varepsilon_{HG} bK[H]_t}
           {1+\frac{1}{2}(-K[G,H]_t + \sqrt{K[G,H]_t^2 + 4K[G]_t})}
     \Biggr\}
\\
  &\times \dfrac{-K[G,H]_t + \sqrt{K[G,H]_t^2 + 4K[G]_t}}{2K}
\end{split}
\end{equation}
where $K[G,H]_t=1-K[G]_t+K[H]_t$.
\end{document}

enter image description here

Choose your own shorthand: my proposal might not comply with other notation you're using.

2
  • hi, thanks for quick reply. is there a way to reduce the font size instead? i would rather keep the format it is in – Spencer Trinh Jul 10 '15 at 23:22
  • 1
    @SpencerTrinh In comparison to most printed works, this is one of the most practised methods. – Leucippus Jul 10 '15 at 23:51

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