hill_obj.m

一个很好的Matlab编制的数据降维处理软件

function [f,df]=hill_obj(x,dims,ii,dd,pars);
% 
% computes the objective function and gradient of the non-convex formulation of MVU. 
%
% copyright by Kilian Q. Weinberger, 2006
%
%
%

% This file is part of the Matlab Toolbox for Dimensionality Reduction v0.4b.
% The toolbox can be obtained from http://www.cs.unimaas.nl/l.vandermaaten
% You are free to use, change, or redistribute this code in any way you
% want for non-commercial purposes. However, it is appreciated if you 
% maintain the name of the original author.
%
% (C) Laurens van der Maaten
% Maastricht University, 2007


    X=reshape(x,dims);
    [df,f]=computegr(X,ii(:,1),ii(:,2),dd);
    df=df(:).*8;

    if(pars.eta>0) % incorporate the trace term
      df=df-pars.eta.*x;
      f=f-pars.eta.*sum(sum(x.^2));
    end;