% --- start of displayed preamble in the book --- % --- end of displayed preamble in the book --- defaultfont:="ptmr8r"; warningcheck:=0; beginfig(1) numeric u; u=5mm; for i:=0 step 10 until 350: draw ((i/360)*10u,3u*sind(i))-- (((i+10)/360)*10u,3u*sind(i+10)); endfor; endfig; end;