%%% $\pi$-decimals

$$\hbox{%
\def\dir{2010/kees-van-der-laan/}
%\pdfximage width70mm{\dir/pihelvetica.jpg}\pdfrefximage\pdflastximage
\pdfximage width70mm{\dir/lunapi.pdf}\pdfrefximage\pdflastximage
\qquad
\pdfximage width70mm{\dir/picwi.jpg}\pdfrefximage\pdflastximage}
$$
How to typeset?

\smallskip

From a CWI calendar of 1972, see the right picture, I borrowed the idea. The
generation of the decimals is not the issue, they are just taken from tables.
In those days it was not possible to scale decimals continually to the size
needed, even arbitrary rotation of the glyphs was hard. Nowadays, we can
achieve this all, as shown in the illustration left, by use of, eg, the
PostScript operator {\tt kshow}.

It is nice to associate a circular spiral with $\pi$-ecimals, because
the circumference of a circle is 2$\pi r$ and its surface  $\pi r^2$.

\beginverbatim
%!!PS -Pi-decimals along a  Spiral cgl 2010 
%BoundingBox:...
200 300 translate .8 0 0 setrgbcolor
/Helvetica findfont 20 scalefont setfont
gsave
	35 0 moveto 90 rotate (3) show 1 0 rmoveto
  (.) show 
	-2 0 rmoveto -10 rotate .995 dup scale
	{pop pop -10 rotate 3 0 rmoveto .995 dup scale}
	(141592653589793238462643383279502884197169399375105820974944592307816406286...)
	kshow

grestore
/Symbol findfont 17 scalefont setfont
110 4 moveto (p) show
showpage
%%EOF
\endverbatim


Explanation

\smallskip

The PS operator {\tt kshow} expects on the stack: {\tt proc string}. The {\tt
proc} is executed between the typesetting of two consecutive characters in the
string. The kerning around the decimal point has been handled separately. The
central $\pi$ is also inserted by PS.

For placing text along an arbitrary path in a workflow the reader is referred
to {\tt Program 11} in Adobe's blue PS book.

\endinput