Hi, list! I have a problem with some graphics in Metapost. I've tried to replicate the Koch curve cited here using ConTeXt: https://en.wikipedia.org/wiki/L-system To my own amusement, the patterns seem to appear. However, when I try with a number from 6, ConTeXt stops doing anything or output looks wrong (see attached PDF, please). \startluacode userdata = userdata or {} function userdata.koch(n) local init = "F" local base = init local replacement = "F+F-F-F+F" for i = 1, n do init = init:gsub(base, replacement) end return init end function userdata.kochlen(n) return string.len(userdata.koch(n)) end function userdata.kochchar(k, n) return string.sub(userdata.koch(n),k,k) end function MP.kochlen(n) mp.print(userdata.kochlen(n)) end function MP.kochchar(k,n) mp.quoted(userdata.kochchar(k,n)) end \stopluacode \startMPpage[instance=doublefun] def koch_curve(expr n, u) = save p; save q; save angle; pair p, last; path q; numeric angle; p:= origin; q := origin; angle := 0; for i = 1 upto lua.MP.kochlen(n): if lua.MP.kochchar(i,n) = "F": q := q -- ((point infinity of q) + dir(angle)); else: if lua.MP.kochchar(i,n) = "+": angle := (angle + 90) mod 360; else: if lua.MP.kochchar(i,n) = "-": angle := (angle - 90) mod 360; fi fi fi endfor; draw q scaled u; enddef; koch_curve(5, 5mm); %koch_curve(6, 5mm); does not give a right output \stopMPpage Maybe there's a fabulous trick to make it work with larger numbers, but I don't know it. I'm aware of a TikZ library for Lindenmayer systems, but it's not a possibility for me in this case (I add the remark just in case). Thank you in advance, Jairo :)