* update the cn_doc of double_buffer

* add more information for double_buffer api

* add optional for parameters have default value

* add more infomation for Variable Reader

* correct the expression

* update the mul cn_api doc

* add optional for parameters have default value

* fix gather_nd scatter_nd_add scatter_nd, test=develop

* fix centerloss, test=develop

* fix the description, test=develop

* fix the doc, test=develop

* expose set_gradient_clip, test=develop

* follow lanxiang's comments, test=develop

* update the has_inf cn_api doc

* alter tensor/LoDtensor to Tensor/LoDTensor

* add reference link of elementwise_pow. test=document_preview

* fix Chinese doc of four API. test=develop, test=document_preview

* fix optional argument.  test=develop, test=document_preview

* fix cn doc accoring to reviews. test=develop, test=document_preview

update the has_nan cn_api doc

alter tensor LoDtensor to Tensor LoDTensor

update cumsum api doc

add Tensor/lodTensor for input x description

alter the optional for parameters have default value

test=develop
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* fix argsort doc
test=document_preview

* fix
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* test=document_preview

* fix
test=document_preview

* fix
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* fix argmax doc
test=document_preview

* fix
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test=develop
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* modify L1DecayRegularizer, L1Decay, L2DecayRegularizer and L2Decay, test=develop

* update cn doc for ones and zeros op

* fix the types of shape in zeros op

* add return type for ones and zeros op

* list all supported data types for zeros and ones op

* improve seq_concat seq_conv e.t api cn doc

* refine doc

* add datatype

* refine doc for api Program, BackwardStrategy, default_start_up_program

* remove wrong binary char to make file not binary

* delete binary file and push a new file as regular one

* change name back since we delete bianry Program_cn on develop

* refine clone doc

* remove additional gitignore

* refine doc about some info

* refine doc about some info

* refine doc about some info

* refine doc about some info

* refine doc about some info

* remove useless info

* refine doc

* fix code

* fix doc error in Program_cn.rst

*  add code and refine doc

* refine clone doc

* add instance norm

* refine switch doc, test=develop, test=document_preview

* add description and sample for member functions, test=develop

* Rewrite the content of load_persistables_cn.rst.

* refine the fill_constant doc test=develop

* fix according the standard test=develop

* fix fill_constant doc test=develop

* fix from standard test=develop

* refine api comments

* refine api comments

* update docs

* update docs

* Rewrite the content of the chain in Reader_cn.rst.

* refine While doc, test=develop

* add refine Switch api doc, test=develop

* refine While, delete Switch, test=develop, test=document_preview

* refine api docs of scale, selu, shape, split, soft_relu. test=develop, test=document_preview

* refine sample codes for api docs, test=develop

* add result comments for sample codes, test=develop

* refine api_cn, test=document_preview

* update cn doc for floor op

* refine the description of floor op

* fix reciprocal doc spec test=develop

* fix doc test=develop

* fix according reviewer advice test=develop

* fix according the review advice test=develop

* fix according the review advice test=develop

* Rewrite the content of load_params_cn.rst.

* use default_main_program instead of _main_program_.

* fix fill_constant_batch_like doc test=develop

* fix doc test=develop

* fix typo test=develop

* fix according reviewer advice test=develop

* fix according review advice test=develop

* Refine fsp_matrix/deformable_conv/fsp_matrix/polygon_box_transform api.

* fix argmin doc
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* test=document_preview

* fix
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* fix relu6 doc
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* fix threshold

* fix
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* fix relu doc
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* fix relu doc

* fix
test=document_preview

* update save_vars and load_vars, test=develop

* modify L1DecayRegularizer, L1Decay, L2DecayRegularizer and L2Decay, test=develop

* add black lines, test=develop

* Rewrite firstn and shuffle functions, test=develop

* improve seq_pool api cn doc test=document_preview

* refine sequence last and first pool doc test=document_preview

* refine sequence_pool dataType test=document_preview

* fix input dtype

* add dataType

* fix datatype