latex loop back formula arrow

Question

I would like to create an equation where 2nd equation is inupt to the first one. I want to write the equation in a figure.

I try using long arrow a

\begin{align}
%\begin{split}
         \rightarrow  \dotr{R}+O_2  &\longrightarrow \dotr{R00}
  %\end{split}
     \label{}
\end{align}
\begin{align}
%\begin{split}
         \dotr{R00} + RH &\longrightarrow ROOH + \dotr{R} \bigg\uparrow
  %\end{split}
     \label{}
\end{align}

See https://tex.stackexchange.com/questions/134773/label-variables-of-equation-using-tikz-without-using-itemize for example. Or https://tex.stackexchange.com/questions/86188/labelling-with-arrows-in-an-automated-way. — Bibi, Jul 22 '20 at 13:25
\begin{align} %\begin{split} \rightarrow \dotr{R}+O_2 &\longrightarrow \dotr{R00} %\end{split} \label{} \end{align}
\begin{align} %\begin{split} \dotr{R00} + RH &\longrightarrow ROOH + \dotr{R} \bigg\uparrow %\end{split} \label{} \end{align} — WBAN_crypto, Jul 22 '20 at 13:40
@Bernard \dotr is used to put black dot on R. It was defined in the start of the document — WBAN_crypto, Jul 22 '20 at 17:43

Bernard · Answer 1 · 2020-07-22T15:55:50.867

4

You can use the \ncloop command from pst-node:

\documentclass{article}
\usepackage{amsmath}
\newcommand{\dotr}[1]{#1^{\bullet}}
\usepackage{pst-node}
\begin{document}
\begin{align}
    \rnode{R1}{ \dotr{\mathrm{R}}}+\mathrm{O}_2 &\longrightarrow \dotr{\mathrm{ROO}}\
     \dotr{\mathrm{ROO}} + \mathrm{RH} &\longrightarrow \mathrm{ROOH} +\dotr{ \rnode{R2}{\mathrm{R}}}
    %
    \psset{linewidth=0.5pt, arrows=<-, arrowinset=0.2, nodesep=2pt}
    \ncloop[angleA=180, armA=1cm, angleB=-90, armB=0.20cm, linearc=0.05]{R1}{R2}%
 \label{}
\end{align}
\end{document}

edited Jul 22 '20 at 15:55

answered Jul 22 '20 at 15:20

Bernard

271,350

thank you very much for your reply. I don't know why the bottom arrow is not appearing in my document. Do I need to add any other package? thanks. – WBAN_crypto Jul 22 '20 at 17:56
I am using my university article class – WBAN_crypto Jul 22 '20 at 18:02

Tanvir · Accepted Answer · 2020-07-22T16:11:30.837

2

The equation in the figure is a chemical equation. Using Bernard's answer and the mhchem package (useful for writing chemical formulas, etc.), following is the code which you may use. The mhchem package takes care of the radical dots in the chemical equation.

\documentclass{article}
\usepackage{amsmath}
\usepackage{pst-node}
\usepackage[version=4, arrows=pgf-filled]{mhchem}
\begin{document}
\begin{align}
    &\rnode{R1}{\ce{R^{.}}} + \ce{O2 -> ROO^{.}} \
    &\ce{ROO^{.} + RH ->}\rnode{R2}{\ce{R^{.}}}
    %
    \psset{linewidth=0.5pt, arrows=<-, arrowinset=0.5, nodesep=2pt}
    \ncloop[angleA=180, armA=1cm, angleB=-90, armB=0.20cm, linearc=0]{R1}{R2}%
\end{align}
\end{document}

edited Jul 22 '20 at 16:11

answered Jul 22 '20 at 15:58

Tanvir

1,232

thank you for the reply. The bottom arrow is not appearing similarly to the previous answer. – WBAN_crypto Jul 22 '20 at 17:57
I am using my university class file – WBAN_crypto Jul 22 '20 at 18:03
How are you compiling the code? Compile the code using XeLaTeX or do this LaTex (x2) -> DVItoPS -> PStoPDF. – Tanvir Jul 22 '20 at 21:40
I am using overleaf – WBAN_crypto Jul 23 '20 at 13:17
In Overleaf, from setting menu, change the compiler from pdfLaTex to XeLaTex. You can get the settings by clicking the menu at the top left of Overleaf. – Tanvir Jul 23 '20 at 13:32
Thankyou very much for your help. It works now. I highly appreciate your patience and help in this regard. Thanks again. – WBAN_crypto Jul 23 '20 at 23:33

latex loop back formula arrow

2 Answers2