# [NTG-context] How to define an array of pens

Otared Kavian otared at gmail.com
Mon Jun 22 09:17:31 CEST 2020

```Hi Hans,

After learning from you how to define an array of colors and paths, I would like to know how is it possible to define a variable pen size.
In the following working example below, I would like to replace

MyPens[j] := pencircle scaled 2pt ;

by something like

MyPens[j] := pencircle scaled (2+j) pt ;

but this does not work (neither do (2+j)*pt).
Is it possible to specify the pen size according to the value of j, without using a structure like

if j == -1 :
MyPens[j] := pencircle scaled 1pt ;
elseif j == 0 :
MyPens[j] := pencircle scaled 2pt ;
else :
MyPens[j] := pencircle scaled 3pt ;
fi

(In my real example I have more than three values for j).

%% begin example-array.tex
\startMPpage
string MyColors[] ;
path   MyPaths [] ;
pen MyPens[] ;
for j = -1 step 1 until 1 :
MyPens[j] := pencircle scaled 2pt ; % I would like to say here (2+j) pt
endfor
MyPaths[-1] := (-1.5cm,1.5cm) -- (1.5cm,1.5cm) ; MyColors[-1] := "magenta" ;
MyPaths[0] := (-2cm,2cm) -- (2cm,-2cm) ; MyColors[0] := "darkyellow" ;
MyPaths[1] := fullcircle scaled 3cm ; MyColors[1] := "darkred" ;
for j = -1 step 1 until 1 :
draw MyPaths[j] withpen MyPens[j] withcolor MyColors[j] ;
endfor
\stopMPpage
%% end example-array.tex

Best regards: Otared
```