eigfem_s.m

FEM tools for caculation of nonlinear problems

function [ E_Vec, eig_Values] = eigFEM_s (K, M, N)

NEG = N;               
opts.maxit = 270;   
opts.tol = 5;   
[eig_vect, eig_val]=eigs(K,M,NEG,'SM',opts);  
eig_val=sqrt(real(eig_val));             

eig_V=diag(eig_val);                     
eig_vect=real(eig_vect);                 

D = size(eig_vect,1);                   

NOM=0; DIN=realmax; S=0;

for i=1:NEG
   for k=1:NEG
      if abs(eig_V(k))>=abs(NOM)
         if abs(eig_V(k))<abs(DIN)
             NOM=eig_V(k); S=k;
         end;
      end;
   end;
   eig_Values(i)=NOM; DIN=NOM;   
   for p=1:D
       E_Vec(p,i)=eig_vect(p,S); 
   end;
   NOM=0;
end;
disp('---- Periods: (s)  ----');
disp('-----------------------');
disp(2*pi./eig_Values);
disp('-----------------------');