FUNCTION kink3,x
;
;  piecewise 3rd order parabolic profile
;
f=make_array(size=size(x))
;
i=where(abs(x) lt 1.)
j=where(x ge 1.)
f(i)=.5+.25*x(i)*(3.-x(i)^2)
f(j)=1.
return,f
END