def s_northarrow (expr rot) =
	valscal=1.2; % scale your north arrow here
	decl:=MagDecl;
	T:=identity;
	picture tmp_pic;
	tmp_pic = image (
		pickup pencircle scaled .3;
		thfill fullcircle scaled 4cm withcolor 1white;
		thdraw fullcircle scaled 3.1cm;
		thdraw fullcircle scaled 4.05cm;
		pickup pencircle scaled .1;
		thdraw fullcircle scaled 3cm;
		thdraw fullcircle scaled 4cm;
		pickup pencircle scaled .2;
		thdraw (dir(45)*2.025cm)--(dir(45)*3.7cm);
		thdraw (dir(135)*2.025cm)--(dir(135)*3.7cm);
		thdraw (dir(225)*2.025cm)--(dir(225)*3.7cm);
		thdraw (dir(315)*2.025cm)--(dir(315)*3.7cm);
		pickup pencircle scaled .1;
		for whereto=0 step 15 until 345:
		  thdraw dir(whereto)*.65cm--dir(whereto)*.9cm;
		  thdraw dir(whereto)*1.4cm--dir(whereto)*1.5cm;
		endfor;
		for whereto=0 step 5 until 355:
		  thdraw dir(whereto)*.65cm--dir(whereto)*.8cm;
		  thdraw dir(whereto)*1.45cm--dir(whereto)*1.5cm;
		endfor; 
		for whereto=0 step 1 until 359:
		  thdraw dir(whereto)*1.94cm--dir(whereto)*2cm;
		endfor; 
		pickup pencircle scaled 1;
		thdraw fullcircle scaled 1cm;
		thdraw fullcircle scaled 1.1cm;
		thdraw fullcircle scaled 1.3cm withpen pencircle scaled .3;
		vald=90-decl;
		texrot=0-decl;
		drawarrow(dir(vald)*-2cm--dir(vald)*2cm) withpen pencircle scaled .2;
		thdraw image(label.top(btex $mg$ etex, (0,0)) scaled .5 rotated texrot;) shifted (dir(vald)*2.04cm);			
		thfill (1.06cm,1.06cm)--(0,.2cm)--(-1.06cm,1.06cm)--(-.2cm,0)--(-1.06cm,-1.06cm)--(0,-.2cm)--(1.06cm,-1.06cm)--(.2cm,0)--cycle;
		thfill (-.2cm,.2cm)--(0,2cm)--(0,0)--cycle;
		thfill (.2cm,-.2cm)--(0,-2cm)--(0,0)--cycle;
		thfill (.2cm,.2cm)--(2cm,0)--(0,0)--cycle;
		thfill (-.2cm,-.2cm)--(-2cm,0)--(0,0)--cycle;
		thfill (.2cm,.2cm)--(-0,2cm)--(0,0)--cycle withcolor 1white;
		thfill (.2cm,-.2cm)--(2cm,0)--(0,0)--cycle withcolor 1white;
		thfill (-.2cm,-.2cm)--(0,-2cm)--(0,0)--cycle withcolor 1white;
		thfill (-.2cm,.2cm)--(-2cm,0)--(0,0)--cycle withcolor 1white;			
		pickup pencircle scaled .2;
		thdraw (-.2cm,.2cm)--(0,2cm)--(.2cm,.2cm)--(2cm,0cm)--(.2cm,-.2cm)--(0,-2cm)--(-.2cm,-.2cm)--(-2cm,0)--cycle;
		thfill fullcircle scaled .56cm withcolor 1white;
		pickup pencircle scaled .1;
		thdraw (.28cm,0)..(0,.28cm)..(-.28cm,0)..(0,-.28cm)..cycle;
		pickup pencircle scaled .4;
		thdraw (.2cm,0)..(0,.2cm)..(-.2cm,0)..(0,-.2cm)..cycle;
		label.bot(btex $N$ etex, (0,2.6cm));
		label.lft(btex $E$ etex, (2.6cm,0));
		label.rt(btex $W$ etex, (-2.6cm,0));
		label.top(btex $S$ etex, (0,-2.6cm));
	);
	thdraw tmp_pic scaled valscal rotatedaround(origin, -rot);
enddef;