# Gaussian on an oblique ray with Tikz

I try to draw a generic Gaussian over a ray, to indicate a possible generic trend. At the moment I have managed to draw both the ray and the Gaussian, but I can't get it to lay on the ray, as changing the coordinates changes the whole graph. In the image it is as I would like it to look, as it came is in the code.

\documentclass[border=2cm]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.8}

\begin{document}

\pgfmathdeclarefunction{gauss}{3}{%
\pgfmathparse{1/(#3*sqrt(2*pi))*exp(-((#1-#2)^2)/(2*#3^2))}%
}

\begin{tikzpicture}
\begin{axis}[
no markers,
domain=0:6,
samples=100,
ymin=0,
xmin=0,
axis lines*=left,
every axis y label/.style={at=(current axis.above origin),anchor=south},
every axis x label/.style={at=(current axis.right of origin),anchor=west},
height=12cm,
width=12cm,
xtick=thick,
ytick=thick,
enlargelimits=false,
clip=false,
axis on top,
grid = major,
]
\begin{scope}[yshift=-\pgflinewidth]

\clip (axis cs:0,0) rectangle (axis cs:6,1);
\end{scope}

\addplot [very thick,black!50!] {gauss (x, 3, 0.8)};
\pgfmathsetmacro\valueB{gauss(1,3,0.09)}
\pgfmathsetmacro\valueA{gauss(1,3,0.8)}
\pgfmathsetmacro\valueC{gauss(1,3,0.8)}

\node[coordinate, pin={Spatial and cognitive distance}] at (axis cs: 3, 0.5){};

\end{axis}

\end{tikzpicture}
\end{document}


Any tips? Thanks a lot <3

Welcome to TeX.SE!!!

If you can use a TikZ picture, it would be very easy. You only have to draw you gaussian function and rotate it.

Like the following example:

\documentclass[border=2mm,tikz]{standalone}

\pgfmathdeclarefunction{gauss}{3}{\pgfmathparse{1/(#3*sqrt(2*pi))*exp(-((#1-#2)^2)/(2*#3^2))}}

\begin{document}
\begin{tikzpicture}
% grid
\draw[help lines]  (0,0) grid[step=0.5] (6,6);
% axes
\draw[latex-latex] (0,6) node [above] {$y$} |- (6,0) node [right] {$x$};
% gaussian function
\draw[rotate=45,red,fill=red,fill opacity=0.2] plot[domain=0:{6*sqrt(2)},samples=100] (\x,{gauss(\x,{3*sqrt(2)},0.7)});
% line
\draw (0,0) -- (6,6);
% axes labels
\foreach\i in {1,...,5}
{
\node at (\i,0) [below] {$\i$};
\node at (0,\i) [left]  {$\i$};
}
\end{tikzpicture}
\end{document}


• Wow thank you so much I didn't know about the possibility of rotating the function. Thank again! Oct 18 at 18:55
• +1: Does the curly bracket syntax {6*sqrt(2)} works out of the box? Oct 19 at 8:26
• @Dr.ManuelKuehner, thanks!! Do you mean without the curly brackets? Yes, it works, I put the curly brackets without thinking, because they are always needed in TikZ coordinates. Oct 19 at 8:35
• Ah, I was assuming that the curly brackets are needed when a calculation is required. Oct 19 at 9:29