# Why arrow decoration position can not coincide with coordination point?

I was trying to add arrow decoration to a curve in a three dimensional plot like following

% !TEX TS-program = xelatex
\documentclass[UTF8]{article}

\usepackage{float}

\usepackage{amssymb}

\usepackage{tikz}
\usepackage{tkz-euclide}
\usetikzlibrary{arrows.meta}
\usetkzobj{all}
\usepackage{graphicx}

\begin{document}

\begin{figure}[H]
\begin{center}
\begin{tikzpicture}[smooth, decoration = {markings, mark = at position 0.4 with {\arrow{Stealth[round, scale = 1.5]}}}]
\centering
\draw[postaction = {decorate}] plot coordinates{(1, 3) (2, 4) (4, 1)};
\end{tikzpicture}
\end{center}
\end{figure}

\end{document}


The compiler will complain the following when I change the decoration position to 0.2 or any value near it

Dimension too large.

I analyzed a few cases, it seems like the compiler will complain whenever the arrow decoration position is near any of the coordination point, in our case, (2, 4).

Is there an explanation? Thanks in advance!

• It has nothing to do with the specific point, but with the fact that the curvature in the neighborhood of this point is large. Very often it is possible to draw an almost identically looking curve in a different way, and the problem does not arise. – user121799 Oct 23 '18 at 19:54
• Your code compiles without error here with MikTeX – AndréC Oct 23 '18 at 19:56
• @marmot What do you mean by drawing an almost identically looking curve? – zyy Oct 23 '18 at 19:58
• @AndréC How did you compile? It compiles fine on my laptop. I used xelatex for compiling. – zyy Oct 23 '18 at 20:00
• I compiled with pdflatex – AndréC Oct 23 '18 at 20:01

What I mean by almost identical path is that there are more harmful and harmless ways to draw very similar curves.

\documentclass[UTF8]{article}
\usepackage{float}

\usepackage{amssymb}

\usepackage{tikz}
\usetikzlibrary{decorations.markings,arrows.meta}
\usetikzlibrary{hobby}

\begin{document}

\begin{figure}[H]
\centering
\begin{tikzpicture}
\begin{scope}[decoration = {markings, mark = at position 0.4 with {\arrow{Stealth[round, scale = 1.5]}}}]
\draw[postaction = {decorate}] plot[smooth] coordinates{(1, 3) (2, 4) (4, 1)};
\end{scope}
\begin{scope}[xshift=4cm,decoration = {markings, mark = at position 0.3 with {\arrow{Stealth[round, scale = 1.5]}}}]
\draw[postaction = {decorate}] (1, 3) to[curve through={(1.4,3.6) .. (2, 4) ..
(2.7,3.3) .. (3.1,2.5)}] (4, 1);
\end{scope}
\end{tikzpicture}
\end{figure}
\end{document}


I stress that I did not make too much effort in reproducing your curve. This is just to tell you that (a) yes, there can be issues and (b) they may go away if you employ alternative ways of drawing such curves.