;	this procedure returns linearly interpolated intermediate
;	values from an OGSE array storing a list of values of a dependent
;	variable; the desired location is that for the value of the 
;	independent variable input.
;	............................................
	pro ogseinterp,index,x,arrayxy,y,z,zz
	if (x lt arrayxy(0,0)) then begin
	  y=arrayxy(1,0)
	  z=arrayxy(2,0)
	  zz=arrayxy(3,0)
	endif
	if (x gt arrayxy(0,index-1)) then begin
	  y=arrayxy(1,index-1)
	  z=arrayxy(2,index-1)
	  zz=arrayxy(3,index-1)
	endif
	for i=0,index-2 do begin
	if ((x ge arrayxy(0,i)) and (x le arrayxy(0,i+1))) then begin
		y=((x-arrayxy(0,i+1))*arrayxy(1,i)+(arrayxy(0,i)-x)*arrayxy(1,i+1))/(arrayxy(0,i)-arrayxy(0,i+1))
		z=((x-arrayxy(0,i+1))*arrayxy(2,i)+(arrayxy(0,i)-x)*arrayxy(2,i+1))/(arrayxy(0,i)-arrayxy(0,i+1))
		zz=((x-arrayxy(0,i+1))*arrayxy(3,i)+(arrayxy(0,i)-x)*arrayxy(3,i+1))/(arrayxy(0,i)-arrayxy(0,i+1))
	endif
	endfor
	return
	end