function map_corners(mp[1]:graphic) local vpx, vpy, vpw, vph, xtleft, ytleft, xtright, ytright, xbright, ybright, xbleft, ybleft, out begin if(NhlClassName(mp).eq."mapPlotClass") getvalues mp "vpXF" : vpx "vpYF" : vpy "vpWidthF" : vpw "vpHeightF" : vph end getvalues xtleft = vpx ytleft = vpy xtright = vpx + vpw ytright = vpy xbright = vpx + vpw ybright = vpy - vph xbleft = vpx ybleft = vpy - vph out = new((/2,4/),float) out(1,:) = (/xtleft,xtright,xbright,xbleft/) out(0,:) = (/ytleft,ytright,ybright,ybleft/) ndctodata(mp,out(1,:),out(0,:),out(1,:),out(0,:)) return((/out/)) else return(new((/2,4/),float)) end if end