Incorrect plotting of e function using Tikz plot

Question 1

I am trying to plot a couple functions in Latex, including an absolute and e function, these are depicted in the following image;

However using the code below, the image that results is:

What is going wrong?

\documentclass{article}\usepackage{tikz}\usepackage{pgfplots}\begin{document}\begin{figure}[h]\centering\begin{tikzpicture}\begin{axis}[    axis lines = left,    xlabel = $t$,    ylabel = {$f(t)$},]%Below the red parabola is defined\addplot [    domain=-0.5:0.5,     samples=100,     color=red,]{sqrt(abs(x))};\addlegendentry{$\sqrt{|t|}$}%Here the blue parabloa is defined\addplot [    domain=-0.5:0.5,     samples=100,     color=blue,    ]    {abs(x)};\addlegendentry{$|t|$}%Here the orange parabloa is defined\addplot [    domain=-0.5:0.5,     samples=200,     color=orange,    ]    {e^(abs(x)-1)}; \addlegendentry{$e^{|t|}-1$} %Here the purple parabloa is defined\addplot [    domain=-0.5:0.5,     samples=100,     color=purple,    ]    {e^(abs(2*x)-1)};\addlegendentry{$e^{|2t|}-1$}\end{axis}\end{tikzpicture}\caption{M1} \label{fig:M1}\end{figure}\end{document}

Question 2

Welcome to TeX.SX! Please make your code compilable (MWE).

Question 3

@TeXnician Is it correct now?

Question 4

Now it is compilable.

Question 5

A couple of things:too few samples, giving you the blunt tip on $\sqrt{|t|}$ ; Don't you meane^(abs(x))-1? That would be $\mathrm{e}^{|t|}-1$ as indicated, and would make sense ase^0=1 and you wantorange_curve(0)=0, soorange_curve should be(e^x)-1 (superfluous brackets for emphasis)

Question 6

Note also that with an even number of samples and a domain that is symmetric around 0, you will not get a sample exactly at x=0. So try 101 samples, instead of 100.

Question 7

At least your red plot can be improved by increasing the samples with:

\addplot [    domain=-0.5:0.5,     samples=1000,     color=red,    smooth,]{sqrt(abs(x))};

Butpgfplots is right plotting your functions: the purple and orange one can not go to y-value 0 (manually calculating results in 1/e for x=0).

Update: Correcting your typos:

%Here the orange parabloa is defined\addplot [    domain=-0.5:0.5,     samples=201,     color=orange,    smooth    ]    {e^(abs(x))-1}; \addlegendentry{$e^{|t|}-1$} %Here the purple parabloa is defined\addplot [    domain=-0.5:0.5,     samples=201,     color=purple,    smooth    ]    {e^(abs(2*x))-1};\addlegendentry{$e^{|2t|}-1$}

Question 8

I think the OP has a typo in the formula definition -- it doesn't match the legend.

Question 9

5000 is a bit overkill, try 201. (Maybe more forsqrt(abs(x)).)

Question 10

@TorbjørnT. Thanks for pointing that out. That was my test document before I looked at the formulas and corrected them...

TeXnician 34.3k9 gold badges69 silver badges135 bronze badges · Answer 1 · 2017-04-06 09:17:23Z

At least your red plot can be improved by increasing the samples with:

\addplot [    domain=-0.5:0.5,     samples=1000,     color=red,    smooth,]{sqrt(abs(x))};

Butpgfplots is right plotting your functions: the purple and orange one can not go to y-value 0 (manually calculating results in 1/e for x=0).

Update: Correcting your typos:

%Here the orange parabloa is defined\addplot [    domain=-0.5:0.5,     samples=201,     color=orange,    smooth    ]    {e^(abs(x))-1}; \addlegendentry{$e^{|t|}-1$} %Here the purple parabloa is defined\addplot [    domain=-0.5:0.5,     samples=201,     color=purple,    smooth    ]    {e^(abs(2*x))-1};\addlegendentry{$e^{|2t|}-1$}

I think the OP has a typo in the formula definition -- it doesn't match the legend.
5000 is a bit overkill, try 201. (Maybe more forsqrt(abs(x)).)
@TorbjørnT. Thanks for pointing that out. That was my test document before I looked at the formulas and corrected them...

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Incorrect plotting of e function using Tikz plot

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