Graphics, Figures & Tables ⇒ How to draw this figure using Tikz?

[zmxm]

I am trying to draw a function $f(x)=(x-0.5)(\frac{x}{x-1})^(-0.5)-x$ using Tikz. I wrote the following code:

Code: Select all

\begin{tikzpicture}[scale=0.7]
		\draw[-stealth,ultra thick] (-0.5,0)--(9,0) node[below]{$x$};
		\draw[-stealth,ultra thick] (0,-0.5)--(0, 4.5);
		\draw[color=blue, thick, domain=0:2] plot (\x, {(\x-0.5)*(\x/(\x-1))^(-0.5)-\x}) node[above, xshift=5pt, yshift=10pt]{$f(x)$};
\end{tikzpicture}

However, I got an error message saying "Dimension too large". Anyone can help? Thanks.

[Stefan Kottwitz]

Hi,

welcome to the forum!

The error occurs because TikZ uses a logarithm for calculating when a non-integer exponent is used, and that's a problem with negative values; a logarithm is not defined for negative values. Also, there's the point x=0 where a division by zero occurs. You get a plot if you change the domain, as I did here:

Code: Select all

\begin{tikzpicture}[scale=0.7]
		\draw[-stealth,ultra thick] (-0.5,0)--(9,0) node[below]{$x$};
		\draw[-stealth,ultra thick] (0,-0.5)--(0, 4.5);
		\draw[color=blue, thick, domain=1.1:8] plot (\x, {(\x-0.5)*(\x/(\x-1))^(-0.5)-\x}) node[above, xshift=5pt, yshift=10pt]{$f(x)$};
\end{tikzpicture}

Click on "Run LaTeX here" to see it.

Stefan