p_stabil.m

这是国外用的研究分岔的完整的M程序

function stability=p_stabil(p,method)

% function stability=p_stabil(point,method)
% INPUT:
%	point solution point
%	method method parameters 
% OUTPUT:
%	stability stability information

% (c) DDE-BIFTOOL v. 2.00, 30/11/2001

if p.kind=='psol'
  if isempty(p.mesh)
    mesh=0:1/(size(p.profile,2)-1):1;
  else
    mesh=p.mesh;
  end;
  rho=method.minimal_modulus;
  max_number=method.max_number_of_eigenvalues;
  if isempty(method.collocation_parameters)
    col=poly_gau(p.degree);
  else
    col=method.collocation_parameters;
  end;
  if(nargin('sys_tau'))==0
    mu=mult_app(p.period,p.profile,mesh,p.degree,rho,max_number,col,p.parameter);
  else 
    d_ac=method.delay_accuracy;
    mu=mult_app(p.period,p.profile,mesh,p.degree,rho,max_number,col,p.parameter,d_ac);
  end;
  if length(mu)
    [y,index_vector]=sort(abs(mu));
    stability.mu=mu(index_vector(length(index_vector):-1:1));
  else
    stability.mu=[];
  end;
else
  real_part=method.minimal_real_part;
  a=method.lms_parameter_alpha;
  b=method.lms_parameter_beta;
  ord=method.interpolation_order;
  h_min=method.minimal_time_step;
  h_max=method.maximal_time_step;
  rho=method.lms_parameter_rho;
  if(nargin('sys_tau'))==0
    [l0,h]=root_app(p.x,real_part,a,b,ord,p.parameter,h_min,h_max,rho);
  else
    d_ac=method.delay_accuracy;
    [l0,h]=root_app(p.x,real_part,a,b,ord,p.parameter,h_min,h_max,rho,d_ac);
  end;
  if length(l0)>method.max_number_of_eigenvalues
    l0=l0(1:method.max_number_of_eigenvalues);
  end;
  stability.h=h;
  stability.l0=l0;
  max_n=method.max_newton_iterations;
  epsi=method.root_accuracy;
  if max_n==0 | isempty(l0)
    stability.l1=[];
    stability.n1=[];
  else
    [l1,n1]=root_nwt(p.x,l0,max_n,epsi,p.parameter);
    if method.remove_unconverged_roots % remove n1 and sort roots
      l1=l1(n1~=-1);
      n1=[];
      if ~isempty(l1)
        [y,index_vector]=sort(real(l1));
        l1=l1(index_vector(length(index_vector):-1:1))';
      end;
    end;
    stability.l1=l1;
    stability.n1=n1;
  end;
end;

return;