anchor.diff:           (log-msg "DBN TEST RMSE: ~{~,5F~^, ~}~%"
                     (map 'list
                          #'get-error
  -                       (dbn-mean-field-errors
  +                       (dbn-mean-field-errors*
                           (make-sampler *test-images*
                                         :max-n (length *test-images*))
                           *dbn/1*))))
  
positive.code:   (log-msg "DBN TEST RMSE: ~{~,5F~^, ~} (~D)~%"
             (map 'list
                  #'get-error
                  (dbn-mean-field-errors (make-sampler *test-images*
                                                       :max-n #+nil
                                                       1000
                                                       (length *test-images*))
                                         (dbn rbm) :rbm rbm))
             (n-inputs trainer))
    (let ((counters-and-measurers
           (make-dbn-reconstruction-misclassification-counters-and-measurers
  
negative.code:     (save-weights (merge-pathnames "mnist-2.bpn" *mnist-dir*)
                    *bpn/2*)))
  
  (defmethod negative-phase (batch (trainer mnist-dbm-trainer) bm)
    (mgl-bm::check-no-self-connection bm)
    (flet ((foo (chunk)
             (mgl-bm::set-mean (list chunk) bm)
  