function [n, G]=ferro(lambda,name)
%lambda in mk, name - Co, Fe, Co
% n is complex refractive index
%G off-diagonal element of epsilon

switch name
case 'Co'
    load CoMy;  %M loaded
case 'Ni'
    load NiMy;  %M loaded
case 'Fe'
   load FeMy;  %M loaded
otherwise
    disp('in ferro not correct material name')
end

Lambda=M(:,1);
if lambda>=Lambda(1)
    G=M(1,4)+i*M(1,5);
    n=M(1,2)+i*M(1,3);
    return
end

JJ=length(Lambda);
if lambda<Lambda(JJ)
    G=M(JJ,4)+i*M(JJ,5);
    n=M(JJ,2)+i*M(JJ,3);
    return
end

for jj=2:JJ-1
    if lambda>=Lambda(jj)

        dlambda=(lambda-Lambda(jj-1))/(Lambda(jj)-Lambda(jj-1));
    G=(M(jj-1,4)+dlambda*(M(jj,4)-M(jj-1,4)))  +i*(M(jj-1,5)+dlambda*(M(jj,5)-M(jj-1,5)));
    n=(M(jj-1,2)+dlambda*(M(jj,2)-M(jj-1,2)))+i*(M(jj-1,3)+dlambda*(M(jj,3)-M(jj-1,3)));
    return
end
end