Matlab Nested Classes, Reference to object of the same class from within -

i trying create tree class in matlab creation of decision tree. when try run script, first time runs through code, can see arrived @ favorable value of f, , v. however, after part of initialization of new nodes left , right, current object empty. how correctly nest reference same class within class such not interfere each other

classdef dtree properties (access = public)      maxdepth;     currentdepth;     features;     left;     right;     f;     v; end   methods       function this=dtree(md, cd, nf, xtrain, ytrain)         % real initialization begins         this.maxdepth = md         this.currentdepth = cd;         this.features = nf;         this.train(xtrain, ytrain);       end        function s = gini(dt, labels)         s = 1;         s = s - (sum(labels > 0.0) ./ numel(labels)) ^ 2;         s = s - (sum(labels < 0.0) ./ numel(labels)) ^ 2;     end      function train(dt, xtrain, ytrain)         if (size(unique(ytrain)) == 1 | dt.currentdepth > dt.maxdepth)             return;         end          mingini = inf;         minf = 0;         minv = inf;         = dt.features             n = 1:size(xtrain, 1)                 idx = xtrain(:, i) > xtrain(n, i);                 gini = dt.gini(ytrain(idx)) + dt.gini(ytrain(~idx));                 if gini < mingini                     mingini = gini;                     minf = i;                     minv = xtrain(n, i);                 end             end         end         dt.f = minf         dt.v = minv         lidx = xtrain(:, dt.f) > xtrain(dt.v, dt.f);         dt.left = dtree(dt.maxdepth, dt.currentdepth + 1, dt.features,xtrain(lidx, :), ytrain(lidx))         dt.right = dtree(dt.maxdepth, dt.currentdepth + 1, dt.features, xtrain(~lidx, :), ytrain(~lidx));      end   end 

end

ans = dtree(1, 1, [2, 5 ,6], xtrain, ytrain);

during execution, dtree properties:

    maxdepth: 1 currentdepth: 1     features: [4 5 2]         left: []        right: []            f: 5            v: 7 

after execution, when type ans ans =

dtree properties:

    maxdepth: 1 currentdepth: 1     features: [4 5 2]         left: []        right: []            f: []            v: [] 

which empty object prior running train.

when deal class methods, need explicitly pass , return object

function = dtree(...)    = this.train(...) end  function dt = train(dt, xtrain, ytrain) ... end 

if don't this, reference object have not updated. need update reference in matlab!