You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: spm_bilinear_condition.m
    path of file: ./repos/bspm/thirdparty/spm12
    
    the code of the file until where you have to start completion: function M0 = spm_bilinear_condition(M0)
% conditions a bilinear operator by suppressing positive eigenmodes
% FORMAT M0 = spm_bilinear_condition(M0)
% M0 - bilinear operator
%__________________________________________________________________________
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging
 

    
function M0 = spm_bilinear_condition(M0)
% conditions a bilinear operator by suppressing positive eigenmodes
% FORMAT M0 = spm_bilinear_condition(M0)
% M0 - bilinear operator
%__________________________________________________________________________
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging
 
% Karl Friston
% $Id: spm_bilinear_condition.m 6937 2016-11-20 12:30:40Z karl $
 
% conditions a bilinear operator by suppressing positive eigenmodes
%==========================================================================
 
% remove unstable modes from Jacobian
%--------------------------------------------------------------------------
dfdx  = M0(2:end