function s=reconst(t)
i=0;
while t>x(i+1)
i=i+1
end
if (t==0) then
   s=f(x(1))
elseif (t==1)
   s=f(x(n+2));
else
  xi=t-x(i);
  s=f(x(i))*(2*xi^3-3*h*xi^2+h^3)/h^3+f(x(i+1))*(-2*xi^3+3*h*xi^2)/h^3+...
    p(i)*(xi^3-2*h*xi^2+h^2*xi)/h^2+p(i+1)*(xi^3-h*xi^2)/h^2;	
end
//