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