[Tex/LaTex] Make a specific dashed parabola curve connecting two points in Tikz

tikz-pgf

I have my tex code for this figure a square 1-2-3-4 with a dashed line connecting p2 and p3 by a intermediate point p23.

How can we make a (
curved) dashed parabola curve (or just any more smooth curve) connecting p2, p23 and p3? Thank you, please make it a short answer.

enter image description here

\begin{tikzpicture}[scale=1,baseline]

\coordinate (p1) at (0,0);

\coordinate (p2) at (0,1);

\coordinate (p3) at (1,0);

\coordinate (p4) at (1,1);

\coordinate (p23) at (.7,.7);

\draw [-,>=latex,line width=0.5pt] (p2) -- (p1);

\draw [-,>=latex,line width=0.5pt] (p4) -- (p3);

\draw [-,>=latex,line width=0.5pt] (p3) -- (p1);

\draw [-,>=latex,line width=0.5pt] (p4) -- (p2);

\draw [-,>=latex, dashed, line width=0.5pt] (p23) -- (p2);

\draw [-,>=latex, dashed, line width=0.5pt] (p23) -- (p3);

\node at (-0.15,-0.15) {1};

\node at (-0.15,1.15) {3};

\node at (1.15,-0.15) {2};

\node at (1.15,1.15) {4};

\end{tikzpicture}
}

Best Answer

Here are three options.

\draw [densely dashed, line width=0.5pt] (p2) edge[bend left=40,looseness=1.5] (p3);
\draw [red,densely dashed, line width=0.5pt] (p2) edge[bend left=40,distance=1cm] (p3);
\draw [blue,densely dashed, line width=0.5pt] (p2) edge[controls=+(0:1) and +(90:1)] (p3);

Adjust the parameters to suit your needs. For more details, read pgfmanual section 70.3, pages 753 onwards.

\documentclass[tikz]{standalone}
\begin{document}
\begin{tikzpicture}[scale=1,baseline]

\coordinate (p1) at (0,0);

\coordinate (p2) at (0,1);

\coordinate (p3) at (1,0);

\coordinate (p4) at (1,1);

\coordinate (p23) at (.7,.7);

\draw [-,>=latex,line width=0.5pt] (p2) -- (p1);

\draw [-,>=latex,line width=0.5pt] (p4) -- (p3);

\draw [-,>=latex,line width=0.5pt] (p3) -- (p1);

\draw [-,>=latex,line width=0.5pt] (p4) -- (p2);

%\draw [-,>=latex, dashed, line width=0.5pt] (p23) -- (p2);
%
%\draw [-,>=latex, dashed, line width=0.5pt] (p23) -- (p3);
\draw [densely dashed, line width=0.5pt] (p2) edge[bend left=40,looseness=1.5] (p3);
\draw [red,densely dashed, line width=0.5pt] (p2) edge[bend left=40,distance=1cm] (p3);
\draw [blue,densely dashed, line width=0.5pt] (p2) edge[controls=+(0:1) and +(90:1)] (p3);

\node at (-0.15,-0.15) {1};

\node at (-0.15,1.15) {3};

\node at (1.15,-0.15) {2};

\node at (1.15,1.15) {4};

\end{tikzpicture}
\end{document}

enter image description here

Related Solutions

[Tex/LaTex] Line up nested tikz enviroments or how to get rid of them

As is explained in How do I draw shapes inside a tikz node? pics can be used for defining new objects. My main problem using pics is how to place where you want because they aren't nodes and positioning them is not so easy.

Following code shows how to define EDFA block.

    EDFA/.pic={
        \begin{scope}[scale=.5]
        \draw (-1,0) coordinate (in) --  (-1,1) -- (1,0) coordinate (out) --  (-1,-1) -- cycle;
        \node[anchor=north,inner sep=2pt] at (0,-1) {$1$};
        \end{scope}

In this case, coordinate (-1,0) will act as west anchor and 1,0 as east. Both point will have an special name for further reference. Every pic is placed according its own origin (0,0). You can use Claudio's answer to Anchoring TiKZ pics for better positioning.

As your example was simple, I'd prefer to star with EDFA and place Source and Sink after it.

\documentclass[]{article}

% tikz
\usepackage{tikz}
\usetikzlibrary{positioning} %relative positioning

\begin{document}

\tikzset{%
    EDFA/.pic={
        \begin{scope}[scale=.5]
        \draw (-1,0) coordinate (in) --  (-1,1) -- (1,0) coordinate (out) --  (-1,-1) -- cycle;
        \node[anchor=north,inner sep=2pt] at (0,-1) {$1$};
        \end{scope}
    }
}

\begin{tikzpicture}[
block/.style={draw},
]

\draw pic (edfa) {EDFA};

\node[block, left=of edfain] (source) {Source};

\node[block, right= of edfaout] (sink) {Sink};

\draw[->] (source) -- (edfain);
\draw[->] (edfaout) -- (sink);

\end{tikzpicture}

\end{document}

I understand that your components are more complex than EDFA because for this particular case an isosceles triangle node with a label will do the work and it can be used as a node and not as a pic:

\documentclass[]{article}

% tikz
\usepackage{tikz}
\usetikzlibrary{positioning} %relative positioning
\usetikzlibrary{shapes.geometric}

\begin{document}

\begin{tikzpicture}[
    block/.style={draw},
    edfa/.style={isosceles triangle, minimum width=1cm, 
         draw, anchor=west, isosceles triangle stretches, 
         minimum height=1cm, label=-80:#1}
]

\node[block] (source) {Source};

\node[edfa=1, right=of source] (edfa) {};

\node[block, right= of edfa] (sink) {Sink};

\draw[->] (source) -- (edfa);
\draw[->] (edfa) -- (sink);

\end{tikzpicture}

\end{document}

[Tex/LaTex] Positioning a node in the beginning of the line

If this is just the start of your diagram, it might be worthwhile to define the circles as nodes and to associate the labels explicitly. The code is longer, but more flexible and more structured.

\documentclass{article}
\usepackage{tikz}
\begin{document}
XXX%
\begin{tikzpicture}%
  [mynode/.style={circle,fill=green,minimum width=5pt,inner sep=0pt,outer sep=0pt},
   mylabel/.style={blue,inner sep=0mm,label distance=0.5ex}
  ]
\node[mynode,label={[mylabel]$bin_1$}]                  (a) at (0,0) {};
\node[mynode,label={[mylabel]$k_1$}]                    (b) at (2,0) {};
\node[mynode,label={[mylabel]$bin_{\mathrm{nyquist}}$}] (c) at (4,0) {};
\draw[red] (a) -- (b) -- (c);
\end{tikzpicture}%
XXX
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Line up nested tikz enviroments or how to get rid of them

[Tex/LaTex] Positioning a node in the beginning of the line

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