% --- start of displayed preamble in the book --- % --- end of displayed preamble in the book --- defaultfont:="ptmr8r"; warningcheck:=0; beginfig(1) u=2.5cm; path p; p= (0,0) {dir 130}.. {dir -130}(0.25u,0){dir 130}.. {dir -130}(0.5u,0){dir 130}.. {dir -130}(0.75u,0){dir 130}.. {dir -130}(u,0); draw p rotated -90; endfig; end;