la.m

fit programme for a serials of data

function y1=L(x,y,x1)
% input x is a vector that contains a list of abscissas
%       y is a vector that cntains a list of ordinates
%       x1 is the number at where the interpolation is to be obained
% output y1 is the la interpolation at x1
n=length(y);
y1=0;
for k=1:n
   p=1;
   for j=1:n
      if j~=k
         p=p*(x1-x(j))/(x(k)-x(j)); 
      end
   end
  y1=y1+p*y(k); 
end