[texhax] TikZ and plain TeX [Update: more issues resolved]

[Suresh Govindachar]

  % I was able to get the expected output from many of the
  % examples in the TikZ manual by adding the ''\usetikzlibrary{}''
  % line shown below.
  %
  % I writing in plain TeX using MikTeX Windows 7, 64 bit;
  % compiling with the command "pdftex foo.tex"
  %
  % Regarding my earlier post about some of the issues I was
  % having, I got a direct reply that resolved the issue with
  % scaling:
  %
  %     Replace curly brackets in \tikzpicture{scale=3}
  %     by square brackets: \tikzpicture[scale=3]
  %
  % and also explained the issue with \frac -- need to:
  %
  %     Replace \frac{1}{2}
  %     with    {1\over2}
  %
  % I was then able to get the thickness option to work by
  % using square brackets "everywhere": with both \tikzpicture
  % and \scope (see code below).
  %
  % What is puzzling is that it doesn't seem to matter whether
  % ">=stealth" is specified with curly or with square brackets.
  %
  % So:  what's the difference between curly and square brackets,
  %      when to use which, and why does it matter for line
  %      thickness but not for arrow style?
  %
  %
  %% Plain TeX file
  \input tikz.tex
 
\usetikzlibrary{intersections,arrows,angles,quotes,calc,decorations.pathmorphing,backgrounds,positioning,fit,petri}

  \baselineskip=12pt
  \hsize=6.3truein
  \vsize=8.7truein

   \tikzpicture[ultra thick]
   \scope[thick]
   \draw (0,0) -- (0,1);
   \endscope
   \scope[thin]
   \draw (1,0) -- (1,1);
   \draw (2,0) -- (2,1);
   \endscope
   % back to the local default of 'ultra thick'
   \draw (3,0) -- (3,1);
   \endtikzpicture

   Stealth arrows with curly brackets:

   \tikzpicture{>=stealth}
   \draw [->] (0,0) arc [start angle=180, end angle=30, radius=10pt];
   \draw [<<-,very thick] (1,0) -- (1.5cm,10pt) -- (2cm,0pt) -- 
(2.5cm,10pt);
   \endtikzpicture

   Again but with square brackets:

   \tikzpicture[>=stealth]
   \draw [->] (0,0) arc [start angle=180, end angle=30, radius=10pt];
   \draw [<<-,very thick] (1,0) -- (1.5cm,10pt) -- (2cm,0pt) -- 
(2.5cm,10pt);
   \endtikzpicture

  % Another issue is that \footnotesize that I happened to find
  % in some example is not recognized
  %   \foreach \s in {1,2,3}{(i-\s) circle (2pt) node {\footnotesize\s}};