Ez legalább lefut az én shellemben is:
#!/bin/sh
S0=S;S1=H;S2=E;S3=L;S4=L;e=echo;b=bc;I=-1;for x in {1..24};
do R=-2;for y in {1..80};do B=0;r=0;i=0;while [ $B -le 32 ];do
r2=`$e "$r*$r"|$b`;i2=`$e "$i*$i"|$b`;i=`$e "2*$i*$r+$I"|$b`;
r=`$e "$r2-$i2+$R"|$b`;: $((B+=1));V=`$e "($r2 +$i2)>4"|$b`;
if [ "$V" -eq 1 ];then break;fi;done; if [ $B -ge 32 ];then
$e -n " ";else U=$(((B*4)/15+30));$e -en "\E[01;$U""m";C=$((C%5));
eval "$e -ne \$E\$S$C";: $((C+=1));fi;R=`$e "$R+0.03125"|$b`
done;$e -e "\E[m\E(\r";I=`$e "$I+0.08333"|$b`;done
Innen: