;	this procedure returns linearly interpolated intermediate
;	values from an array storing a list of values of a dependent
;	variable; the desired location is that for the value of the 
;	independent variable input.
;	............................................
	pro interp2,index,x,arrayxy,y
	if (x lt arrayxy(0,0)) then begin
	  y=arrayxy(2,0)
	endif
	if (x gt arrayxy(0,index)) then begin
	  y=arrayxy(2,index)
	endif
	for i=0,index-1 do begin
	if ((x ge arrayxy(0,i)) and (x le arrayxy(0,i+1))) then begin
		y=((x-arrayxy(0,i+1))*arrayxy(2,i)+(arrayxy(0,i)-x)*arrayxy(2,i+1))/(arrayxy(0,i)-arrayxy(0,i+1))
	endif
	endfor
	return
	end