Guide to LaTeX (4th Edition) (Tools and Techniques

142 Chapter 5. Mathematical Formulas
5.4.8 Framed or side-by-side formulas
Displayed formulas or equations may be put into vertical boxes of appropriate
! width, that is, in a \parbox command or minipage environment. Within the vertical
box, the formulas are horizontally centered or left justified with indentation
\mathindent according to the selected document class option.
Vertical boxes may be positioned relative to one another just like single
characters (Sections 4.7.3 and 4.7.7). In this way the user may place displayed
formulas or equations side by side.
α = f (z) (5.8)
β = f (z 2 ) (5.9)
γ = f (z 3 ) (5.10)
x = α 2 − β 2
y = 2αβ
The left-hand set of equations
is set in a \parbox of width
4 cm, the right-hand set in one
of width 2.5 cm, while this text
is inside a minipage of width
4.5 cm.
\parbox{4cm}{\begin{eqnarray} \alpha &=& f(z)...\end{eqnarray}}
\hfill \parbox{2.5cm}{\begin{eqnarray*}
x &=& \alphaˆ2 - \betaˆ2\\ y &=& 2\alpha\beta \end{eqnarray*}}
\hfill \begin{minipage}{4.5cm} The left-hand ... \end{minipage}
Vertical boxes can also be useful when equation numbers are placed in an
! unconventional manner. The eqnarray environment generates an equation number
for every line, which may be suppressed with \nonumber. To add a vertically
centered equation number to a set of equations, for example,
P(x) = a0 + a1x + a2x 2 + · · · + anx n
P(−x) = a0 − a1x + a2x 2 − · · · + (−1) n anx n (5.11)
the following text may be given:
\parbox{10cm}{\begin{eqnarray*} ... \end{eqnarray*}} \hfill
\parbox{1cm}{\begin{eqnarray}\end{eqnarray}}
The actual set of equations is produced here in the eqnarray* environment,
within a vertical box of width 10 cm, followed by an empty eqnarray environment
in a box of width 1 cm that generates the equation number. Both boxes are
vertically aligned along their center lines.
Emphasizing formulas by framing requires no new construction elements. It
! is sufficient to put them into an \fbox (Section 4.7.7). Text formulas a + b
are simply framed with \fbox{$a+b$}. For displayed formulas, \displaystyle
(Section 5.5.2) must be issued, else they are set as text formulas.
is produced with
∞
0
f (x) dx ≈
n
wie xif (xi)
\[\fbox{$\displaystyle \intˆ\infty_0 f(x)\,\mathrm{d}x ..$}\]
An alternative method to frame displayed equations is with the A M S-L AT E X \boxed
command, page 270.
i=1