[pstricks] grid as background in an environment

[Martin Buchmann]

Herbert,

>draw the grid by yourself.

Well, that's a good idea! I never thought of that but in your 
approach i have to give the number of lines. I would prefer to set 
the distance between the lines, let's say 0.5cm in each direction for 
a square grid and then calculate the number of grid lines in each 
direction.

Something like this:

\makeatletter
\newcommand\grid[2]{{%
	\newdimen\xMax \xMax=#2%
	\newdimen\yMax \yMax=#1%
	\newcount\xLines
	\newcount\yLines
	\newdimen\dx \dx=0.5cm  \xLines=\xMax \divide\xLines by \dx%
	\newdimen\dy \dy=0.5cm  \yLines=\yMax \divide\yLines by \dy%
	\psset{unit=1pt, linecolor=yellow}%
	\advance\xLines by 1%
	\advance\yLines by 1%
	\yMax=\dy \multiply\yMax by \yLines
	\xMax=\dx \multiply\xMax by \xLines
	\advance\xLines by 1%
	\advance\yLines by 1%
	\multido{\rA=0+\strip at pt\dx}{\xLines}{\psline(\rA,0)(\rA,\yMax)}%
	\multido{\rA=0+\strip at pt\dy}{\yLines}{\psline(0,\rA)(\xMax,\rA)}%
}}
\makeatother

I'm not sure if this is really bug free. I never did arithmetics in 
TeX beforebut it is working for my minimal example.

Thanks
   Martin

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