3

Hi im trying to show some math relationships in two columns

\documentclass{article}
\usepackage{mathrsfs,amsmath, mathtools}
\usepackage{extarrows}
\begin{document}
\begin{equation*}
\begin{aligned}[c]
1\\[10pt]
\delta{(t)}\\[10pt]
u(t)\text{\footnotemark}\\[10pt]
sgn(t)\text{\footnotemark}\\[10pt]
rect(t)\\[10pt]
sinc(t)\\[10pt]
tri(t)\\[10pt]
sinc^2(t)\\[10pt]
\end{aligned}
\qquad\xlongleftrightarrow{\mathscr{F}}\qquad
\begin{aligned}[c]
&2\pi\delta{(\omega)}\\[10pt]
&1\\[10pt]
&\pi\delta{(w)}+\frac{1}{j\omega}\\[10pt]
&\frac{2}{jw}\\[10pt]
&sinc(\frac{\omega}{2\pi})\\[10pt]
&rect(\frac{\omega}{2\pi})\\[10pt]
&sinc^2(\frac{\omega}{2\pi})\\[10pt]
&tri(\frac{\omega}{2\pi})\\[10pt]
\end{aligned}
\end{equation*}
\end{document}

But the output does not align the equations correctly. Fourier transform pairs

  • As the items in the two aligned have different heights they of course does not align. In stead use a single construction and multiple alignment points – daleif Aug 9 '16 at 10:07
  • Could you provide me with a basic example that would allow me to use the format I desire above? – JS60 Aug 9 '16 at 10:09
  • also never use math italic for multi-letter words such as rect, the font is designed to separate the letters to look like a product of variables not a word – David Carlisle Aug 9 '16 at 10:09
  • Ok so just surround the rect,tri sinc in a \text{} ? – JS60 Aug 9 '16 at 10:11
  • 2
    @JS60 no, no, no please don't use \text for that, it is not what it is mena to be used for, if they do not already exists, define them using \DeclareMathOperator – daleif Aug 9 '16 at 10:32
4

Here is an example to show the alignment, still not sure what those \footnotemark are for

\documentclass{article}
\usepackage{mathrsfs,amsmath, mathtools}
\usepackage{extarrows}
\DeclareMathOperator\sinc{sinc}
\DeclareMathOperator\sgn{sgn}
\DeclareMathOperator\rect{rect}
\DeclareMathOperator\tri{tri}

\begin{document}
\begin{equation*}
\begin{alignedat}{3}
&1 &&&& 2\pi\delta{(\omega)} \\
&\delta{(t)}&&&& 1 \\
&u(t)\text{\footnotemark}&&&& \pi\delta{(w)}+\frac{1}{j\omega} \\
&\sgn(t)\text{\footnotemark}&&&& \frac{2}{jw} \\
&\rect(t)&& 
\qquad\xlongleftrightarrow{\mathscr{F}}\qquad
&& \sinc(\frac{\omega}{2\pi}) \\
&\sinc(t)&&&& \rect(\frac{\omega}{2\pi}) \\
&\tri(t)&&&& \sinc^2(\frac{\omega}{2\pi}) \\
&\sinc^2(t)&&&& \tri(\frac{\omega}{2\pi} 
\end{alignedat}
\end{equation*}
\end{document}
3

An alternative with array:

enter image description here

\documentclass{article}
\usepackage{mathrsfs,mathtools}
\usepackage{extarrows}
\usepackage{multirow}

\begin{document}
\[
\renewcommand\arraystretch{2}
\begin{array}{lcl}
1                           &   &2\pi\delta(\omega)                 \\
\delta{(t)}                 &   &1                                  \\
u(t)\text{\footnotemark}    &   &\pi\delta{(w)}+\frac{1}{j\omega}   \\
sgn(t)\text{\footnotemark}  &   &\frac{2}{jw}                       \\
rect(t)                     &   &sinc(\frac{\omega}{2\pi})          \\
sinc(t)                     &   &rect(\frac{\omega}{2\pi})          \\
tri(t)                      &   &sinc^2(\frac{\omega}{2\pi})        \\
sinc^2(t)                   &
        \multirow{-8}*{$\qquad\xlongleftrightarrow{\mathscr{F}}\qquad$}
                                &tri(\frac{\omega}{2\pi})
\end{array}
\]
\end{document}

The sinc, tri, etc are function names, they should be in upright shape, i.e. declare them as math operators (\DeclareMathOperator\sinc{sinc}, ...) as is done in other answers.

2

You need to use some sort of array, if you want to keep entries aligned with one another.

For the middle arrow, there are two possibilities: set it in the vertical center or at the top. Take your pick.

\documentclass{article}
\usepackage{mathrsfs,amsmath, mathtools,array}
\usepackage{extarrows}

\DeclareMathOperator\sinc{sinc}
\DeclareMathOperator\sgn{sgn}
\DeclareMathOperator\rect{rect}
\DeclareMathOperator\tri{tri}

\begin{document}

\begin{equation*}
\renewcommand{\arraystretch}{2}
\begin{array}{@{} >{\displaystyle}l c >{\displaystyle}l @{}}
1 &\hphantom{\xlongleftrightarrow{\mathscr{F}}}& 2\pi\delta{(\omega)} \\
\delta{(t)} && 1 \\
u(t)\text{\footnotemark} && \pi\delta{(w)}+\frac{1}{j\omega} \\
\sgn(t)\text{\footnotemark} && \frac{2}{jw} \\
\rect(t) && \sinc\Bigl(\frac{\omega}{2\pi}\Bigr) \\
\sinc(t) && \rect\Bigl(\frac{\omega}{2\pi}\Bigr) \\
\tri(t) && \sinc^2\Bigl(\frac{\omega}{2\pi}\Bigr) \\
\sinc^2(t) && \tri\Bigl(\frac{\omega}{2\pi}\Bigr)
\end{array}
\settowidth{\dimen0}{$\displaystyle\pi\delta{(w)}+\frac{1}{j\omega}$}
\makebox[0pt][r]{%
  $\xlongleftrightarrow{\mathscr{F}}$%
  \hspace{\dimen0}%
  \hspace{2\arraycolsep}%
}
\end{equation*}

\bigskip

\begin{equation*}
\renewcommand{\arraystretch}{2}
\begin{array}{@{} >{\displaystyle}l c >{\displaystyle}l @{}}
1 &\xlongleftrightarrow{\mathscr{F}}& 2\pi\delta{(\omega)} \\
\delta{(t)} && 1 \\
u(t)\text{\footnotemark} && \pi\delta{(w)}+\frac{1}{j\omega} \\
\sgn(t)\text{\footnotemark} && \frac{2}{jw} \\
\rect(t) && \sinc\Bigl(\frac{\omega}{2\pi}\Bigr) \\
\sinc(t) && \rect\Bigl(\frac{\omega}{2\pi}\Bigr) \\
\tri(t) && \sinc^2\Bigl(\frac{\omega}{2\pi}\Bigr) \\
\sinc^2(t) && \tri\Bigl(\frac{\omega}{2\pi}\Bigr)
\end{array}
\end{equation*}

\end{document}

enter image description here

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