tikz-pgf
I am trying to plot some parametric curves, however I always get an an error saying "Dimension is too large". Is there any way to fix this?
\begin{tikzpicture}[scale=.2]
\draw[very thin,color=gray,step=.5cm,dashed] (-8,-8) grid (4,4);
\draw[<->, blue] (-8,0) -- (4,0) node[below right] {$x$};
\draw[<->, blue] (0,-8) -- (0,4) node[left] {$y$};
\draw [red, thick, domain=-10:1.1, samples=40]
plot ({\x^3-3*\x}, {3*\x^2-9} );
\end{tikzpicture}
If you want to reproduce a hand drawn curve and use the smooth interpolation it is better to use less points:
\documentclass[]{standalone}
\usepackage{xcolor}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}[ytick={30,45},yticklabels={min,max},xtick={10,200,1024},xticklabels={$10$,$20$,$1024$}]
\addplot[smooth] coordinates {
(0,45)
(200,28)
(400,40)
(800,30)
(1024,28)
};
\end{axis}
\end{tikzpicture}
\end{document}
(Note the "fake" x-scale, as in your hand drawn picture)
Alternatively you can plot a function or a polynomial that follows a similar curve: for example cos(x)/x.
The domain=-3:3,samples=50 is an option to \addplot which should be enclosed as [domain=-3:3,samples=50] and in your code\addplot has no argument giving it a file of data or a function to plot. \addplot [domain=-3:3,samples=50] {x}; for example will plot y=x from -3 to +3.
In order to plot parametric curves rather than giving {x}, \addplot should receive \addplot [domain=-3:3,samples=50]({x^3-3*x},{3*x^2-9}); or to work with some variable t rather than x (to me at least this feels more intuitive!), \addplot [domain=-3:3,samples=50,variable=\t]({t^3-3*t},{3*t^2-9}); will plot x(t)=t^3-3d and y(t)=3t^2-9 for t between -3 and 3.
See Plotting parametric curves, in particular cmhughes' answer for a full example of parametric plots with pgfplots.
Best Answer