anchor.diff:  (is
    (n-times-average
     100
  -  (let ((a9a-dtree (make-dtree 2 a9a-dim a9a-datamatrix a9a-target :max-depth 20)))
  +  (let ((a9a-dtree (make-dtree 2 a9a-datamatrix a9a-target :max-depth 20)))
       (test-dtree a9a-dtree a9a-datamatrix-test a9a-target-test)))
    82.23217010498047d0
    :test #'approximately-equal)
  
positive.code:   20
    (trivial-garbage:gc :full t)
    (let* ((a9a-forest
             (make-forest 2 a9a-dim a9a-datamatrix a9a-target
                          :n-tree 500 :bagging-ratio 0.1 :min-region-samples 5 :n-trial 10 :max-depth 10))
           (a9a-refine-dataset (make-refine-dataset a9a-forest a9a-datamatrix))
           (a9a-refine-test (make-refine-dataset a9a-forest a9a-datamatrix-test))
  
negative.code:     20
      (trivial-garbage:gc :full t)
      (let* ((letter-forest
               (make-forest letter-n-class letter-datamatrix letter-target
                            :n-tree 500 :bagging-ratio 0.1 :min-region-samples 5 :n-trial 10 :max-depth 10))
             (letter-refine-dataset (make-refine-dataset letter-forest letter-datamatrix))
             (letter-refine-test (make-refine-dataset letter-forest letter-datamatrix-test))
  