# [pstricks] Operating individual parts of data / LowLevel syntax

Jorge Nto jorgento at gmail.com
Fri Dec 11 00:24:01 CET 2009

Good evening!

Now I am almost ready with my application. A data set of three columns, from
which the two first store coordinates and the third one a radius, should be
plotted as circles.
The problem is that as I use the command \pscircle, the radius must be
scaled down.  So in the following code snipset:

\def\psLabelPlot{\pst at object{psLabelPlot}}
\def\psLabelPlot at i#1{\begin at SpecialObj\expandafter\psLabelPlot at ii#1}
\def\psLabelPlot at ii #1{\psLabelPlot at iii#1}
\def\psLabelPlot at iii#1 #2 #3 #4 #5 #6 {%
\pscircle(#2,#4){0.5}%

\@ifnextchar D{\psLabelPlot at iii}{\end at SpecialObj}%
}

I would like to replace in the line \pscircle(#2,#4){0.5}% I would like to
use the parameter #6 (but scaled) instead of the 0.5
I tried RPN syntax, but of course it did not work (\pscircle(#2,#4){#6 50
div}) the multiplication sign doesnt work either (\pscircle(#2,#4){#6*0.02})

How can I do this? if there is a solution, I could replace the scaling
factor by  \psxunit, or \psyunit or a combination of both "\psyunit?"

I have another question. I still don't know how the advanced 'subject' is
called: "LaTex macros?" "Latex Internals".
The PSTricks books explain (and very well) the Ps-Functions at a high level
but, which of all the books on the DANTE project can explain me the advanced
(low level) syntax?
@i, @ii, @iii, expandafter and so on?

Thanks a lot, you make a wonderful work by bringing us up more and more