function lmb = beam_ev(n,l)
%-------------------------------------------------------------------------
% Function name: beam_ev 
% Description: finds eigenvalues for the 2D beam/plate dry vibrations  
% Note: eigenvalues for the rigid modes are also included
%-------------------------------------------------------------------------

% Variables
% n     :   number of the desired eigenvalues
% l     :   beam/plate half-length 
% lmb   =   vector of eigenvalues

lmb = zeros(1,n);
p=0;
q=0;
for k=1:n
    if rem(k-1,2) == 0
        temp = fzero(@(x) tan(x)+tanh(x),p*pi);
        lmb(k) = temp/l;
        p=p+1; 
    else
        temp = fzero(@(x) -1*tan(x)+tanh(x),q*pi);
        lmb(k) = temp/l;
        q=q+1;
    end
end