misc

tikz/x-2-quadratic-function/x-2-quadratic-function.tex

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+\documentclass[varwidth=true, border=2pt]{standalone}
+
+\usepackage{pgfplots}
+\usepackage{tikz}
+\usetikzlibrary{patterns}
+
+    \tikzset{
+        hatch distance/.store in=\hatchdistance,
+        hatch distance=10pt,
+        hatch thickness/.store in=\hatchthickness,
+        hatch thickness=2pt
+    }
+
+    \makeatletter
+    \pgfdeclarepatternformonly[\hatchdistance,\hatchthickness]{flexible hatch}
+    {\pgfqpoint{0pt}{0pt}}
+    {\pgfqpoint{\hatchdistance}{\hatchdistance}}
+    {\pgfpoint{\hatchdistance-1pt}{\hatchdistance-1pt}}%
+    {
+        \pgfsetcolor{\tikz@pattern@color}
+        \pgfsetlinewidth{\hatchthickness}
+        \pgfpathmoveto{\pgfqpoint{0pt}{0pt}}
+        \pgfpathlineto{\pgfqpoint{\hatchdistance}{\hatchdistance}}
+        \pgfusepath{stroke}
+    }
+
+\begin{document}
+\begin{tikzpicture}
+    \begin{axis}[
+        legend pos=north east,
+        axis x line=middle,
+        axis y line=middle,
+        grid = major,
+        width=8cm,
+        height=8cm,
+        grid style={dashed, gray!30},
+        xmin= 0,     % start the diagram at this x-coordinate
+        xmax= 2,    % end   the diagram at this x-coordinate
+        ymin= 0,     % start the diagram at this y-coordinate
+        ymax= 2,   % end   the diagram at this y-coordinate
+        xlabel=$x$,
+        ylabel=$y$,
+        %xticklabels={-2,-1.6,...,2},
+        %yticklabels={-8,-7,...,8},
+        tick align=outside,
+        enlargelimits=true,
+        tension=0.08]
+      % plot it
+      \addplot[domain=0:2, red, thick,samples=500] {x*x};
+      \addplot[pattern=flexible hatch,
+        area legend,
+        pattern color=blue, domain=0:1,samples=500] {x*x} \closedcycle;
+      \addlegendentry{$f(x)=x^2$}
+      \addlegendentry{$\int_0^1 x^2 \mathrm{d} x$}
+    \end{axis} 
+\end{tikzpicture}
+\end{document}