# Example: Intersection of

Published 2008-06-08 | Author: Rasmus Pank Roulund

This example shows how the intersection of mechanism of Tikz work. Notice how a horizontal line is made from point B to allow the calculation to be done.

Caption: In a fixed exchange regime it might not be possible to reach internal balance (full employment and price stability) and external balance (some given level of net export) using only fiscal policy. At point B only point C and D can be reached via fiscal policy. Only by devaluing the country is able to reach the optimum level at point A.

Author: Rasmus Pank Roulund

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% Intersection of
% Author: Rasmus Pank Roulund
\documentclass{minimal}
\usepackage{tikz}
\usetikzlibrary{arrows}
\begin{document}
\begin{tikzpicture}[
scale=5,
axis/.style={very thick, ->, >=stealth'},
important line/.style={thick},
dashed line/.style={dashed, thin},
pile/.style={thick, ->, >=stealth', shorten <=2pt, shorten
>=2pt},
every node/.style={color=black}
]
% axis
\draw[axis] (-0.1,0)  -- (1.1,0) node(xline)[right]
{$G\uparrow/T\downarrow$};
\draw[axis] (0,-0.1) -- (0,1.1) node(yline)[above] {$E$};
% Lines
\draw[important line] (.15,.15) coordinate (A) -- (.85,.85)
coordinate (B) node[right, text width=5em] {$Y^O$};
\draw[important line] (.15,.85) coordinate (C) -- (.85,.15)
coordinate (D) node[right, text width=5em] {$\mathit{NX}=x$};
% Intersection of lines
\fill[red] (intersection cs:
first line={(A) -- (B)},
second line={(C) -- (D)}) coordinate (E) circle (.4pt)
node[above,] {$A$};
% The E point is placed more or less randomly
\fill[red]  (E) +(-.075cm,-.2cm) coordinate (out) circle (.4pt)
node[below left] {$B$};
% Line connecting out and ext balances
\draw [pile] (out) -- (intersection of A--B and out--[shift={(0:1pt)}]out)
coordinate (extbal);
\fill[red] (extbal) circle (.4pt) node[above] {$C$};
% line connecting  out and int balances
\draw [pile] (out) -- (intersection of C--D and out--[shift={(0:1pt)}]out)
coordinate (intbal);
\fill[red] (intbal) circle (.4pt) node[above] {$D$};
% line between out og all balanced out :)
\draw[pile] (out) -- (E);
\end{tikzpicture}
\end{document}
%%% Local Variables:
%%% mode: latex
%%% TeX-master: t
%%% End:


• #1 David B., July 23, 2013 at 12:10 p.m.

I tried the "intersection of" feature, and it took me a long time to figure out that it is very sensitive to whitespace. On my slide I had a variation on this line:

\draw [pile] (out) -- (intersection of A--B and out--[shift={(0:1pt)}]out) coordinate (extbal);


I had unwittingly added a space between "out" and ") coordinate":

\draw [pile] (out) -- (intersection of A--B and out--[shift={(0:1pt)}]out ) coordinate (extbal);


And this resulted in cryptical errors like:

! Package pgf Error: No shape named out  is known.


This was very puzzling, because I was convinced that "out" was actually pretty well defined. But apparently pgf was searching for a key named "out " instead of "out": after I removed the above-mentioned space, the slide compiled.

In case it matters: on my system (linux mint 14) pgf version 2.10-1 is installed. The texlive-* packages are almost all either version 2012.20120611-2 or 2012.20120611-4 (the texlive-binaries package is version 2012.20120628-3build1). The installed latex-beamer package is version 3.10-2.