# Equation Parameters alignment

You should *not* leave a blank line between `\end{equation}`

and `\begin{conditions}`

or the description might be detached from the equation.

Nor you should have a blank line before `\begin{equation}`

under any circumstance.

On the other hand, such a long description of variables is quite likely to produce bad page breaks, be it detached or not from the equation.

Probably a simple list environment is better for such cases: the equals signs are not necessary and can be replaced by the verb *is*.

Here's a fixed version of your code; I've made several small fixes and you can compare them with your version. After `=`

there is no capital letter: they're heavy and don't go along with the commas; `ith`

should be `$i$th`

and `at x`

should *always* be `at $x$`

(even better, `at~$x$`

). Ending with `\endtabularx\\[\baselineskip]`

will produce a warning.

```
\usepackage{array,tabularx,calc}
\newlength{\conditionwd}
\newenvironment{conditions}[1][where:]
{%
#1\tabularx{\textwidth-\widthof{#1}}[t]{
>{$}l<{$} @{${}={}$} X@{}
}%
}
{\endtabularx\\[\belowdisplayskip]}
\begin{document}
\citet{hernandez1992probabilistic} further refines the PROLAM model and uses a virtual work calculation (see equation \ref{eqn:PROLAM deflection} to calculate the deflection ($\Delta$) which can be used in standard elastic deflection MOE calculations \ref{eqn:MOE4pt}.
\begin{equation}
\Delta = \displaystyle\sum_{i=1}^{n} \left[\left(\frac{M_x m_x}{E_c I_i}+\frac{kV_xv_x}{A_iG_i}\right) \times \Delta_x \right]
\label{eqn:PROLAM deflection}
\end{equation}
\begin{conditions}
$\Delta$ & The total glulam beam deflection at $x$,\\
$M_x$ & The bending moment at $x$ caused by actual loading,\\
$m_x$ & The bending moment at $x$ caused by a unit load at the midspan of the beam,\\
$V_x$ & The shear at $x$ caused by actual loading,\\
$v_x$ & The shear at $x$ caused by a unit load at the midspan of the beam,\\
$k$ & A form factor (1.2 for rectangular section),\\
$E_c$ & A constant MOE value used in the transformed cross section,\\
$I_i$ & The moment of inertia of the ith transformed cross section at x,\\
$A_i$ & The transformed area at the ith transformed cross section at x,\\
$G_i$ & The shear modulus of the ith transformed cross section at x,\\
$\Delta_x$ & The increment at which calculations are performed,\\
$n$ & The total number of increments along the beam length.\\
\end{conditions}
\end{document}
```

Here's with a list.

```
\documentclass{article}
\usepackage{array,tabularx,calc}
\usepackage{natbib}
\usepackage{enumitem}
\newlength{\conditionwd}
\newenvironment{conditions}[1][where:]
{%
#1\tabularx{\textwidth-\widthof{#1}}[t]{
>{$}l<{$} @{${}={}$} X@{}%>{\raggedright\arraybackslash}X@{}
}%
}
{\endtabularx\par\addvspace{\belowdisplayskip}}
\begin{document}
\citet{hernandez1992probabilistic} further refines the PROLAM model and uses
a virtual work calculation (see equation~\ref{eqn:PROLAM deflection}) to calculate
the deflection ($\Delta$) which can be used in standard elastic deflection MOE
calculations~\ref{eqn:MOE4pt}
\begin{equation}
\Delta = \sum_{i=1}^{n} \left[
\left(\frac{M_x m_x}{E_c I_i}+\frac{kV_xv_x}{A_iG_i}\right) \times \Delta_x
\right]
\label{eqn:PROLAM deflection}
\end{equation}
where
\begin{itemize}[labelindent=0pt,leftmargin=*,widest=$M_x$,align=left,itemsep=0pt]
\item[$\Delta$] is the total glulam beam deflection at $x$,
\item[$M_x$] is the bending moment at $x$ caused by actual loading,
\item[$m_x$] is the bending moment at $x$ caused by a unit load at the midspan of the beam,
\item[$V_x$] is the shear at $x$ caused by actual loading,
\item[$v_x$] is the shear at $x$ caused by a unit load at the midspan of the beam,
\item[$k$] is a form factor ($1.2$ for rectangular section),
\item[$E_c$] is a constant MOE value used in the transformed cross section,
\item[$I_i$] is the moment of inertia of the $i$th transformed cross section at $x$,
\item[$A_i$] is the transformed area at the $i$th transformed cross section at $x$,
\item[$G_i$] is the shear modulus of the $i$th transformed cross section at $x$,
\item[$\Delta_x$] is the increment at which calculations are performed,
\item[$n$] is the total number of increments along the beam length.
\end{itemize}
\end{document}
```

There is an indent on the line where the `conditions`

environment begins. In your example, the `conditions`

environment is defined as

```
\newenvironment{conditions}[1][where:]
{%
#1\tabularx{\textwidth-\widthof{#1}}[t]{
>{$}l<{$} @{${}={}$} X@{}
}%
}
{\endtabularx\\[\belowdisplayskip]}
```

So when the `conditions`

environment is called with the default value `where:`

for its optional argument, "where:" is written, and a `tabularx`

environment begins. The width of this `tabularx`

is defined to be `\textwidth`

minus the width of "where:". Hence, the indent at the beginning of the line is not taken into account in the width of the `tabularx`

: as you can see on your on your picture, the extra width on the parameters description matches the length of an indent. So just adding `\noindent`

right before the `conditions`

environment will solve the spacing issue.

Also, the `tabularx`

environment called by `conditions`

already places the first column in math mode, so you should not place manually the content of every cell between `$`

.