
How to draw this picture in latex?
Any help will be appreciated.
Here is a start, showing three different ways of connecting two nodes: straight lines (--), bent ones of limited curvature (to[bend ...]), and bent ones with greater flexibility but more complex (.. controls +() and +() ..).
\documentclass[border=2pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{decorations.markings}
\begin{document}
\begin{tikzpicture}
[decoration={markings,mark=at position 0.5 with {\arrow{stealth}}},
blob/.style={circle,fill,minimum width=2pt,inner sep=0pt},
flow/.style={postaction={decorate}}
]
\node[blob,label=above:N] (N) at (0, 0) {};
\node[blob,label=below:S] (S) at (0,-3) {};
\draw[flow] (S) .. controls +(-1.5,0) and +(-1.5,0) .. node[left]{$a_1$} (N);
\draw[flow] (S) to[bend left=40]node[left]{$a_2$} (N);
\draw[flow] (S) -- node[left] {$a_3$} (N);
\draw[flow] (S) to[bend right=40]node[right]{$a_4$} (N);
\draw[flow] (S) .. controls +(1.5,0) and +(1.5,0) .. node[right]{$a_5$} (N);
\end{tikzpicture}
\end{document}
\documentclass{}...\begin{document}etc. As it is, most of our users will be very reluctant to touch your question, and you are left to the mercy of our procrastination team who are very few in number and very picky about selecting questions. You can improve your question by adding a minimal working example (MWE) that more users can copy/paste onto their systems to work on. If no hero takes the challenge we might have to close your question. – Dr. Manuel Kuehner Mar 23 '17 at 11:28tikz-cdorpst-nodepackage. – Bernard Mar 23 '17 at 11:57