[Tex/LaTex] Problem with a TikZ/Geogebra plot of an exponential function (even if using CVS version definition)


I wanted to graph the function f(x)=(-1+4x^2)*e^2 in a coordinate system. Using "Export Graphics View as pgf/TikZ" in Geogebra I got the following code (here shown after I did some minor changes regarding color and arrow style).

[scale=2,line cap=round,line join=round,x=1.0cm,y=1.0cm]
\draw [color=black!70,dash pattern=on 1pt off 1pt, xstep=0.5cm,ystep=0.5cm] (-1.45,-1.28) grid (1.45,2.48);
\draw[->,line width=1,color=black] (-1.45,0) -- (1.45,0);
\foreach \x in {-1,1}
\draw[shift={(\x,0)},color=black] (0pt,2pt) -- (0pt,-2pt) node[below] {\footnotesize $\x$};
\draw[color=black] (1.31,0.04) node [anchor=south west] { x};
\draw[->,line width=1,color=black] (0,-1.28) -- (0,2.48);
\foreach \y in {-1,1,2}
\draw[shift={(0,\y)},color=black] (2pt,0pt) -- (-2pt,0pt) node[left] {\footnotesize $\y$};
\draw[color=black] (0.05,2.28) node [anchor=west] { y};
\clip(-1.45,-1.28) rectangle (1.45,2.48);
\draw[line width=1,color=black!80,fill=black!80,fill opacity=0.6, smooth,samples=50,domain=0.0:0.5] plot(\x,{(4*\x^2-1)*2.7183^\x}) -- (0.5,0) -- (0,0) -- cycle;
\draw[line width=1,smooth,samples=100,domain=-1.5:1.5] plot(\x,{(-1+4*\x^2)*2.7183^\x});

The code above gave me this result:

The way the graph looks before adding code to preamble

I tried installing TikZ CSV from this page following steps given here but this only flooded the log in "Undefined control sequence" messages.

Instead I tried using Jake's answer code to improve the exp-function. Then the result looked a bit better but still not correct:

The way the graph looks after adding Jake's code to preamble

Here is how the original graph is shown in Geogebra (Wolfram Alpha shows similar results):

The way the graph looks in Geogebra

Obviously the exp-code is not helping enough, so maybe there still is a bug in that? Can someone help me with this? Would it be possible to plot the graph correctly in some other way? If so, what would that code look like?

Best Answer

GeoGebra is a wonderful tool for creating interactive tools for students, and while the code it produces using its export feature is pretty impressive, it can usually not beat a hand-made solution, especially for readability and cleanness.

Here's a hand-made solution using pgfplots


% arara: pdflatex
% !arara: indent: {overwrite: true, trace: on}


% axis style
\pgfplotsset{every axis/.append style={
              axis x line=middle,
              axis y line=middle,
              axis line style={<->},
              framed/.style={axis background/.style ={draw=black}},

% arrow style


            minor xtick={-3,-1,...,3},
            minor ytick={-3,-1,...,3},
        \addplot[-] expression[domain=-2.3:2.3,samples=50]{(-1+4*x^2)*exp(x)};
        \addplot[fill] expression[domain=0:0.5]{(-1+4*x^2)*exp(x)}\closedcycle;

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