# Latex plots wrong curve

I have the following code

\begin{tikzpicture}[domain=0:10]
\begin{scope}[xshift=4cm, scale=1]

\draw[->] (-0.2,0) -- (10.5,0) node[right] {$x$};
\draw[->] (0,-0.5) -- (0,6.5) node[above] {$f(x)$};
\draw[color=red] plot (\x,{0.0018 *pow(\x,3)-0.0728* pow(\x,2)+0.8947
*\x+1.0173}) ;
\draw[color=blue,domain=8:10] plot (\x,{-0.0001109 *(\x)^5+0.0041994*(\x)^4-

0.060293* (\x)^3+0.43576 *(\x)^2-1.80134* (\x)+5.3364}) ;

\end {scope}
\end{tikzpicture}


It gives me the following picture:

It just doesn't make sense, it it supposed to look like that:

Can somebody help me?

• can you add the matlab version of the code? – percusse Nov 23 '17 at 16:16

## 1 Answer

You should use PGFPlots instead of drawing the coordinate system on your own.

\documentclass{article}
\usepackage{pgfplots}
\pgfplotsset{compat=newest}

\begin{document}

\begin{tikzpicture}
\begin{axis}[domain=0:10, axis y line = middle, axis x line = middle]
\addplot[red] {0.0018 * pow(x,3)-0.0728* pow(x,2)+0.8947
*x+1.0173};
\addplot[blue, domain=8:10] {-0.0001109 *(x)^5+0.0041994*(x)^4-0.060293* (x)^3+0.43576 *(x)^2-1.80134* (x)+5.3364};
\end{axis}
\end{tikzpicture}

\end{document}