function disc,N,Radius,show=show
z=0
a=findgen(2*N)*(!Pi*2/(2*N))
x=cos(a)
y=sin(a)
Centre=[N/2.,N/2.]
x=x*Radius+Centre(0)
y=y*Radius+Centre(1)
xx=polyfillv(x,y,N,N)
z=fltarr(N,N)
z(xx)=255
	if keyword_set(show) then begin
window,/free,xsi=(N > 150),ysi=(N > 150),xpos=0,ypos=0
tv,z
	endif
	return,z
end