% --- start of displayed preamble in the book --- input cmarrows setup_cmarrows(arrow_name = "tripplearrow"; parameter_file = "cmr10.mf"; macro_name = "drawtripple"); setup_cmarrows(arrow_name = "extensiblebrace"; parameter_file = "cmr10.mf"; macro_name = "drawbrace"); setup_cmarrows(arrow_name = "paralleloppositelefthalfarrows"; parameter_file = "cmr10.mf"; macro_name = "drawparallel"); % --- end of displayed preamble in the book --- defaultfont:="ptmr8r"; warningcheck:=0; beginfig(1) numeric u; u=7mm; z0=origin; z1-z0=(2u,0); z2-z1=(3u,2u); drawtripple z0..z1..{dir-120}z2; draw z0{up}..z2; drawbrace z1{up}..z2; drawbrace z1{down}..z0; drawparallel z0{dir-150}..{up}z2; endfig; end;