Long \sqrt in two lines
Some suggestions
Don't use
eqnarray
-- it's badly deprecated. If you need to align consecutive equations on some chosen marker (say, an=
symbol), use thealign
environment of theamsmath
package.The term
\exp
is a math operator and doesn't take an argument. Really.Don't over-use
\left
and\right
to auto-size parentheses. Among other things, using\left
and\right
introduces extra white-space, which isn't desirable here, is it?Instead of
\bigg(\!-\!\frac...
, write\biggl(-\frac...
. (And, use\biggr)
instead of just\bigg)
.) TeX's spacing rules treat-
as a unary operator if it's preceded by an object to typemath-open
;\biggl(
is such an object, whereas\bigg(
is not.The equation is simply too wide to fit inside the text block, it has to be broken up into two lines. I suggest you use a
split
environment inside anequation
environment for this purpose. And, use\biggl\{
in the first row and\biggr\}^{1/2}
in the second to denote the start and end of the material whose square root is being taken.
\documentclass{article}
\usepackage{amsmath} % for 'split' environment
\begin{document}
\begin{equation}
\begin{split}
y&=\pm\biggl\{
\frac{Q}{2\pi \sigma_y\sigma_z u C(x,y,z) }
\exp\biggl(-\frac{y^2}{2\sigma_y^2}\biggr) \\
&\qquad\quad \times\biggl[
\exp\biggl(-\frac{(z-H)^2}{2\sigma_z^2}\biggr)+
\exp\biggl(-\frac{(z+H)^2}{2\sigma_z^2}\biggr)
\biggr]
\biggr\}^{\!1/2}
\end{split}
\end{equation}
\end{document}
Given the twocolumn
constraint, multline
is still an option:
\documentclass[twocolumn]{article}
\usepackage{amsmath} % for 'multline' environment
\begin{document}
And a multline equation ...
\begin{multline}
y=\pm\biggl\{
\frac{Q}{2\pi \sigma_y\sigma_z u C(x,y,z) }
\exp\biggl(-\frac{y^2}{2\sigma_y^2}\biggr) \\
\times\biggl[
\exp\biggl(-\frac{(z-H)^2}{2\sigma_z^2}\biggr)+
\exp\biggl(-\frac{(z+H)^2}{2\sigma_z^2}\biggr)
\biggr]
\biggr\}^{\!1/2}
\end{multline}
\end{document}