tkz-fn — Graphs of functions with LuaLaTeX

Current release: 2026/10/19 version 1.00c

tkz-fn draws graphs of functions with TikZ; every computation is done by Lua. It is the successor of tkz-fct: gnuplot, fp.sty, tkz-base and --shell-escape are no longer needed.

Features

• Curves y = f(x), parametric and polar curves; the curve is interrupted where the function is not defined and at vertical asymptotes.
• Tangent lines and one-sided tangent lines, areas under a curve or between two curves, Riemann sums (left, right, mid, inf, sup).
• Points on a curve, coordinates, texts, vertical and horizontal lines, data.
• Results computed by Lua and written in the text: values, derivatives, integrals, Riemann sums.
• Two coordinate spaces: computations are done in the units of the coordinate system (xstep, ystep), drawing is done in centimeters.
• Numbers written in the American (3.14, (a, b)) or the French (3,14, ]a ; b[) format.
• Axes as in school textbooks (arrow at one or both ends) or "box" axes as with pgfplots, chosen with an option (no environment).
• Optional bridge to tkz-elements: the points defined by tkz-fn are available in the table z.

Requirements

• LuaLaTeX
• TikZ (loaded by the package, with the library plotmarks)

tkz-fn does not need tkz-base or tkz-euclide. All its macros begin with \tkzFn, so it can be used together with tkz-fct.

Installation

The package consists of two files: tkz-fn.sty and tkz_fn.lua. Put them in a folder known to TeX, for example texmf/tex/latex/tkz-fn, or in the folder of your document.

Quick start

% !TEX TS-program = lualatex
\documentclass{article}
\usepackage{tkz-fn}
\begin{document}
\begin{tikzpicture}
  \tkzFnInit[xmin=-2,xmax=4,ymin=-3,ymax=6]
  \tkzFnGrid
  \tkzFnAxes
  \tkzFnDef{f}{x^2 - 2*x - 1}
  \tkzFnDraw[thick,red](f)
  \tkzFnTangent[blue,kl=1.5,kr=1.5](f,3)
\end{tikzpicture}

$f'(3) = \tkzFnPrint{diff(f,3)}$
\end{document}

Expressions are Lua expressions: x^2, sin(x), ln(x), exp(x), sqrt(x), pi, e.

Documentation

• doc/tkz-fn-en.pdf: documentation in American English
• doc/tkz-fn-fr.pdf: documentation in French

The sources are in doc/latex-en and doc/latex-fr (class tkz-doc, LuaLaTeX, makeindex).

License

This work may be distributed and/or modified under the conditions of the LaTeX Project Public License, either version 1.3c of this license or (at your option) any later version. See LICENSE and lppl-1-3c.txt.

This work has the LPPL maintenance status "maintained". The Current Maintainer of this work is Alain Matthes.