[Tex/LaTex] Make a smoother plot of functions with pgfplots

pgfplotstikz-pgf

The following code gives me a plot which is not very smooth. It looks like several points (with spacing 0.5 in the horizontal direction) are drawn first and then connected by straight lines. What options do I have to modify to make it smoother? Thanks.

\documentclass[]{standalone}
\usepackage{xcolor}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
scale=0.8,
axis lines=middle,
grid=major,
xmin=-5,
xmax=5,
ymin=-5,
ymax=5,
xlabel=$x$,
ylabel=$y$,
xtick={-4,-3,...,5},
ytick={-4,-3,...,4},
tick style={very thick}
]
\addplot[domain=-6:6, blue, ultra thick] {x^3-x};
\end{axis}
\end{tikzpicture}
\end{document}

Best Answer

You can use the option smooth:

\documentclass{standalone}
\usepackage{xcolor}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
scale=0.8,
axis lines=middle,
grid=major,
xmin=-5,
xmax=5,
ymin=-5,
ymax=5,
xlabel=$x$,
ylabel=$y$,
xtick={-4,-3,...,5},
ytick={-4,-3,...,4},
tick style={very thick},
smooth
]
\addplot[domain=-6:6, blue, ultra thick] {x^3-x};
\end{axis}
\end{tikzpicture}
\end{document}

Related Solutions

[Tex/LaTex] plotting two time series with bounds

This happens because PGFPlots only uses one "stack" per axis: You're stacking the second confidence interval on top of the first. The easiest way to fix this is probably to use the approach described in "Is there an easy way of using line thickness as error indicator in a plot?": After plotting the first confidence interval, stack the upper bound on top again, using stack dir=minus. That way, the stack will be reset to zero, and you can draw the second confidence interval in the same fashion as the first:

\documentclass{standalone}
\usepackage{pgfplots, tikz}

\usepackage{pgfplotstable}

\pgfplotstableread{
temps   y_h y_h__inf    y_h__sup    y_f y_f__inf    y_f__sup    

1   0.237340    0.135170    0.339511    0.237653    0.135482    0.339823    
2   0.561320    0.422007    0.700633    0.165871    0.026558    0.305184    
3   0.694760    0.534205    0.855314    0.074856    -0.085698   0.235411    
4   0.728306    0.560179    0.896432    0.003361    -0.164765   0.171487    
5   0.711710    0.544944    0.878477    -0.044582   -0.211349   0.122184    
6   0.671241    0.511191    0.831291    -0.073347   -0.233397   0.086703    
7   0.621177    0.471219    0.771135    -0.088418   -0.238376   0.061540    
8   0.569354    0.431826    0.706882    -0.094382   -0.231910   0.043146    
9   0.519973    0.396571    0.643376    -0.094619   -0.218022   0.028783    
10  0.475121    0.366990    0.583251    -0.091467   -0.199598   0.016664    
}{\table}

\begin{document}
\begin{tikzpicture}

    \begin{axis}
    % y_h confidence interval
    \addplot [stack plots=y, fill=none, draw=none, forget plot]   table [x=temps, y=y_h__inf]   {\table} \closedcycle;
    \addplot [stack plots=y, fill=gray!50, opacity=0.4, draw opacity=0, area legend]   table [x=temps, y expr=\thisrow{y_h__sup}-\thisrow{y_h__inf}]   {\table} \closedcycle;
    % subtract the upper bound so our stack is back at zero
    \addplot [stack plots=y, stack dir=minus, forget plot, draw=none] table [x=temps, y=y_h__sup] {\table};

    % y_f confidence interval
    \addplot [stack plots=y, fill=none, draw=none, forget plot]   table [x=temps, y=y_f__inf]   {\table} \closedcycle;
    \addplot [stack plots=y, fill=gray!50, opacity=0.4, draw opacity=0, area legend]   table [x=temps, y expr=\thisrow{y_f__sup}-\thisrow{y_f__inf}]   {\table} \closedcycle;

    % the line plots (y_h and y_f)    
    \addplot [stack plots=false, very thick,smooth,blue]  table [x=temps, y=y_h]   {\table};
    \addplot [stack plots=false, very thick,smooth,blue]  table [x=temps, y=y_f]   {\table};
    \end{axis}

\end{tikzpicture}
\end{document}

[Tex/LaTex] Make plot smoother in pgfplots

The default surface plot of pgfplots uses two triangles for each rectangular patch segment. Usually, the diagonal does not matter much -- but in this case, it really matters and the result is unsuitable.

Note that shader=interp appears to select the other diagonal (unintentionally, but it does). A simple solution would be to add shader=interp, unless you really need the grid lines.

\documentclass{standalone}

\usepackage{pgfplots}
\usepgfplotslibrary{patchplots}
\pgfplotsset{compat = 1.12}

\newcommand{\param}{2.0}

\begin{document}
        \begin{tikzpicture}
          \begin{axis}[view={40}{50}]
            \addplot3[surf, domain = 0:1, y domain = 0:1, unbounded coords=jump,
                shader=interp,
                samples = 25]
            {x^(-\param-1)*y^(-\param-1)*(x^(-\param)+y^(-\param)-1)^(-1/\param-2)+\param*x^(-\param-1)*y^(-\param-1)*(x^(-\param)+y^(-\param)-1)^(-1/\param-2)};
        \end{axis}
      \end{tikzpicture}
\end{document}

enter image description here

Best Answer

Related Solutions

[Tex/LaTex] plotting two time series with bounds

[Tex/LaTex] Make plot smoother in pgfplots

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