I have been dabbling with the **TikZ package** to create some diagrams relevant to a first year microeconomics course. The following diagram of a price ceiling may be useful to others wishing to integrate similar diagrams into their LaTeX documents or Beamer presentations. To use, insert the following code anywhere you like within a .tex document (you must include `\usepackage{tikz}`

in your header):

#### INSERT INTO .TEX DOCUMENT

\begin{tikzpicture}[domain=0:5,scale=1,thick] \usetikzlibrary{calc} %allows coordinate calculations. %Define linear parameters for supply and demand \def\dint{4.5} %Y-intercept for DEMAND. \def\dslp{-0.5} %Slope for DEMAND. \def\sint{1.2} %Y-intercept for SUPPLY. \def\sslp{0.8} %Slope for SUPPLY. \def\pfc{2.5} %Price floor or ceiling \def\demand{\x,{\dslp*\x+\dint}} \def\supply{\x,{\sslp*\x+\sint}} % Define coordinates. \coordinate (ints) at ({(\sint-\dint)/(\dslp-\sslp)},{(\sint-\dint)/(\dslp-\sslp)*\sslp+\sint}); \coordinate (ep) at (0,{(\sint-\dint)/(\dslp-\sslp)*\sslp+\sint}); \coordinate (eq) at ({(\sint-\dint)/(\dslp-\sslp)},0); \coordinate (dint) at (0,{\dint}); \coordinate (sint) at (0,{\sint}); \coordinate (pfq) at ({(\pfc-\dint)/(\dslp)},0); \coordinate (pfp) at ({(\pfc-\dint)/(\dslp)},{\pfc}); \coordinate (sfq) at ({(\pfc-\sint)/(\sslp)},0); \coordinate (sfp) at ({(\pfc-\sint)/(\sslp)},{\pfc}); % DEMAND \draw[thick,color=blue] plot (\demand) node[right] {$P(q) = -\frac{1}{2}q+\frac{9}{2}$}; % SUPPLY \draw[thick,color=purple] plot (\supply) node[right] {Supply}; % Draw axes, and dotted equilibrium lines. \draw[->] (0,0) -- (6.2,0) node[right] {$Q$}; \draw[->] (0,0) -- (0,6.2) node[above] {$P$}; %Price floor and ceiling lines \draw[dashed,color=black] plot (\x,{\pfc}) node[right] {$P_c$}; \draw[dashed] (pfp) -- (pfq) node[below] {$Q_d$}; \draw[dashed] (sfp) -- (sfq) node[below] {$Q_s$}; \draw[->,baseline=5] ($(0,{\pfc})+(-1.5,0.7)$) node[label= left:Price Ceiling] {} -- ($(0,{\pfc})+(-.1,0.1)$); \end{tikzpicture}

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