# Create curved arrow using tkz-tab package

I would like to ask if I can create a curved arrow using the tkz-tab package. Here is the documentation of the package. There are some examples of creating arrows, but not curved ones.

The reason I need them is to show that a function is either convex or concave. If someone can provide another solution, I would be grateful to hear.

Here is what I have:

\documentclass{article}
% XeLaTeX

\usepackage{fontspec}
\setmainfont{Times}
\usepackage{amsmath,amssymb}
\usepackage{tkz-tab}

\begin{document}
\begin{tikzpicture}

\tkzTabInit{$x$ /.8 , $f''(x)$ /.8, $f'(x)$/.8 , $f(x)$/.8}{$-\infty$, $0$ , $+\infty$};
\tkzTabLine{,+,z,-}
\tkzTabLine{,+,t, +}
\tkzTabLine{,\nearrow,z,\nearrow}

\end{tikzpicture}

\end{document}


which yields:

• What code have you got at the moment? I mean: obviously you can use TikZ for this. What's the issue? – cfr Jun 24 '16 at 1:32
• @cfr Is it clear now? If I use the tikz package how am I supposed to embed it in the tikzpicture environment? – thanasissdr Jun 24 '16 at 1:41
• Thanks. Yes. That's much clearer. Doesn't this diagram have a name? If so, try searching. It looks really familiar. I'm sure there are a couple of questions about them - maybe something helpful. (But I don't remember the name to search.) – cfr Jun 24 '16 at 1:47
• @cfr It is called table of signs. I tried googling that, but there were no results. Anyway... – thanasissdr Jun 24 '16 at 1:53
• Probably you have to use regular TikZ similar to what's done on page 69. – cfr Jun 24 '16 at 2:40

Is this kind of what you were looking for? I use the list of available points in the tkz-tab-manual and use calc library to calculate coordinates of new points.

\documentclass{article}

\usepackage{amsmath,amssymb}
\usepackage{tikz,tkz-tab}
\usetikzlibrary{calc}

\begin{document}
\begin{tikzpicture}
\tkzTabInit{$x$ /.8 , $f''(x)$ /.8, $f'(x)$/.8 , $f(x)$/.8}{$-\infty$, $0$ , $+\infty$};
\tkzTabLine{,+,z,-}
\tkzTabLine{,+,t, +}
\tkzTabLine{,,z,}
\draw[red,thick,->,shorten >= 2pt,shorten <= 4pt] ($.5*(N14) + .5*(M14) + (0,.5mm)$) to [bend right=25] ($.5*(N23) + .5*(M13)$);
\draw[red,thick,->,shorten >= 7pt,shorten <= 7pt] ($.5*(N23) + .5*(M23) + (0,.5mm)$) to [bend right=25] ($.7*(N34) + .3*(M24) + (0,.7mm)$);
\end{tikzpicture}

\end{document}

• You need to upload an image, not a pdf file. Just click the picture icon and select the file to upload. – Peter Grill Jun 24 '16 at 9:04