some doubts about argmax_layer (may be bug)

[WangJinyin]

Issue summary

some doubts about argmax_layer.

Suppose out bottom blob is [[11, 12, 13, 14, 15, 16, 17, 18, 19, 20]], with shape (1, 10).

• about LayerSetup

  if (has_axis_) { axis_ = bottom[0]->CanonicalAxisIndex(argmax_param.axis()); CHECK_GE(axis_, 0) << "axis must not be less than 0."; CHECK_LE(axis_, bottom[0]->num_axes()) <<"axis must be less than or equal to the number of axis."; CHECK_LE(top_k_, bottom[0]->shape(axis_)) << "top_k must be less than or equal to the dimension of the axis."; }

  The second check CHECK_LE(axis_, bottom[0]->num_axes()) should be CHECK_LT?

  First CHECK_GE(axis_, 0) and second check CHECK_LE(axis_, bottom[0]->num_axes()) are not required, because after CanonicalAxisIndex(argmax_param.axis()), 0 <= axis_ < num_axes().

• when out_max_val = true, top_k = 5, has_axis = true, axis = 1

  The top blob will be [[20, 19, 18, 17, 16]], with shape (1, 5).
  But it should be [[[9, 8, 7, 6, 5], [20, 19, 18, 17, 16]]], with shape (1, 2, 5).

  When out_max_val = true and has_axis = true, we will lose max_index.
  Maybe we should add one dimension just before axis.

• out_max_val = false, top_k = 5, has_axis = false

  The top blob will be [[[9, 8, 7, 6, 5]]], with shape (1, 1, 5).
  But it should be [[9, 8, 7, 6, 5]], with shape (1, 5).

  When num_axes of bottom blob less than 3, num_axes of top blob will be 3.
  But sometimes this is wrong.
  May be something worng with:
  if ( num_top_axes < 3 ) num_top_axes = 3; (argmax_layer.cpp line 37)

Steps to reproduce

Tried solutions

System configuration

• Operating system:
• Compiler:
• CUDA version (if applicable):
• CUDNN version (if applicable):
• BLAS:
• Python version (if using pycaffe):
• MATLAB version (if using matcaffe):

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