printing points based on 4 - way symmetry
echo " ( ▁ " , $ x + $ xc , " , ▁ " , $ y + $ yc , " ▁ ) STRNEWLINE " ; echo " ( ▁ " , - $ x + $ xc , " , ▁ " , $ y + $ yc , " ▁ ) STRNEWLINE " ; echo " ( ▁ " , $ x + $ xc , " , ▁ " , - $ y + $ yc , " ▁ ) STRNEWLINE " ; echo " ( ▁ " , - $ x + $ xc , " , ▁ " , - $ y + $ yc , " ▁ ) STRNEWLINE " ;