0

How can I plot y=x^(-0.5)?

\documentclass[border=2pt]{standalone}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}

                \draw[->] (0,0) -- (6.2,0) node[right] {$Q$};
                \draw[->] (0,0) -- (0,6.2) node[above] {$P$};
                \draw[thick,purple,smooth] plot (\x,{(2)^(0.5)*(\x)^(-0.5)});
                \draw[thick,brown,smooth] plot (\x,{(0.5)^(0.5)*(\x)^(-0.5)});

\end{tikzpicture}
\end{document}
  • Plotting 1/sqrt x perhaps? – user31729 Feb 27 '15 at 11:10
2

This is a pgfplots solution, but it works with normal plot as well.

\documentclass[border=2pt]{standalone}
\usepackage{pgfplots}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}
  \begin{axis}[xmax=3]
    \draw[->] (0,0) -- (6.2,0) node[right] {$Q$};
    \draw[->] (0,0) -- (0,6.2) node[above] {$P$};
    \addplot[domain=0.001:3,samples=201,purple,thick,smooth]{2^0.5*x^-0.5};
    \addplot[domain=0.001:3,samples=201,brown,thick,smooth]{0.5^0.5*x^-0.5};    
      %          \draw[thick,purple,smooth] plot (\x,{(2)^(0.5)*(\x)^-0.5});
      %          \draw[thick,brown,smooth] plot (\x,{(0.5)^(0.5)*(\x)^-0.5});
  \end{axis}
\end{tikzpicture}
\end{document}

enter image description here

  • @LaRiFaRi: Why? – user31729 Feb 27 '15 at 11:20
1

You must add a valid domain because by default is (-5,5) and x^0.5 is not defined for negative values.

\documentclass[border=2pt]{standalone}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}

                \draw[->] (0,0) -- (6.2,0) node[right] {$Q$};
                \draw[->] (0,0) -- (0,6.2) node[above] {$P$};
                \draw[thick,purple,smooth] plot [domain=0:5] (\x,{(2)^(0.5)*(\x)^(-0.5)});
                \draw[thick,brown,smooth] plot [domain=0:5] (\x,{(0.5)^(0.5)*(\x)^(-0.5)});

\end{tikzpicture}
\end{document}

enter image description here

1

You could make your formula a bit easier and I would recommend for this:

% arara: pdflatex

\documentclass[border=2pt]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.11}

\begin{document}
\begin{tikzpicture}
    \begin{axis}[%
        ,xlabel=$Q$
        ,ylabel=$P$
        ,xmin=0,xmax=6.2
        ,ymin=0,ymax=6.2
        ,axis x line=bottom
        ,axis y line=left
        ,every axis x label/.style={at={(current axis.right of origin)},anchor=west}
        ,every axis y label/.style={at={(current axis.north west)},anchor=south}
        ]
    \addplot[%
        ,samples at={0.05,0.1,...,6}
        ,smooth
        ,thick
        ,purple
        ] {sqrt(2/x)};
    \addplot[%
        ,samples at={0.05,0.1,...,6}
        ,smooth
        ,thick
        ,brown
        ] {sqrt(0.5/x)};
    \end{axis}
\end{tikzpicture}
\end{document}

enter image description here

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.