# Making certain equation environments larger

I'm writing a lab report in LaTeX that involves a lot of equations. I wish for some equations to be larger than normal, owing to the fact that there are a lot of terms that are in the exponential, and this makes it tougher to read. How can I ensure some equations are larger, while others remain the same size?

\documentclass[10pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{geometry}
\geometry{a4paper, total={14.5cm, 23cm}}
\begin{document}
The amplitude $u_2 (x_2, y_2)$ at the back focal plane is given by
$$u_2 (x_2, y_2) = c \int \int \tau (x_1, y_1) e^{\frac{-2 \pi i (x_1x_2 + y_1y_2)}{\lambda f_1}} dx_1 dy_1$$
\end{document}


I wish for this particular equation to be larger than the rest, so that the exponential term is easily read. I also wish to use the equation environment, since I want to number the equations.

• If you use \exp{...} instead of e^{...} your exponents will be easier to read. Commented Apr 12, 2015 at 18:35

You are already using package amsmath and have therefore \tfrac, which puts the fraction in the math style \textstyle:

\documentclass[10pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{geometry}
\geometry{a4paper, total={14.5cm, 23cm}}

\newcommand*{\diff}{\mathop{}\!d}

\begin{document}
The amplitude $u_2 (x_2, y_2)$ at the back focal plane is given by
$$u_2 (x_2, y_2) = c \int \int \tau (x_1, y_1) e^{\frac{-2 \pi i (x_1x_2 + y_1y_2)}{\lambda f_1}} dx_1 dy_1$$

Now \verb|\tfrac| (text style fraction) is used for the exponential term.
Also a double integral is used and \verb|d| as kind of operator:
$$u_2 (x_2, y_2) = c \iint \tau (x_1, y_1)\,e^{\tfrac{-2 \pi i (x_1x_2 + y_1y_2)}{\lambda f_1}} \diff x_1 \diff y_1$$
\end{document}


There is also \dfrac (fraction in display style), but this is IMHO too large for an exponent.

Remarks:

• The double integral is set by \iint with better spacing than \int\int.
• The differential d is set as left sided operator with some extra space before, see macro \diff.
• Also I have added a small space before the basis e for a better visual appearance.