* add hinge_embedding_loss

* fix test_API

* test_API succeed

* add English doc

* fixed using of expired fluid api

* fix doc

* fix doc and rm python/paddle/fluid/layers/loss.py

* get raw python/paddle/fluid/layers/loss.py back

* fix Examples bug in English doc

* unique -> flatten

* fix api code

* fix English doc

* fix functional loss English doc

* fix Example doc

* .numpy() -> paddle.unique()

* fix unique

* fix label_item_set

* modified judgment equation

* Got a beautiful loss equation

* use paddle.to_tensor

* fix loss and add static check

* fix loss and add static check

* delta -> margin

* Revert "Align CTC grad scale same with ESPNet (#34729)"

This reverts commit 10f9644c.

* ctc grad compute on gpu

* dygraph support more ctc grad scale

* scale for 1.x

* fix unitest

* fix unitest

* format code

* fix unittest

* fix log info

* unittest cov

* fix format;notest,test=cpu,coverage

* skip ctc_loss egs;test=cpu

* warpctc grad cov;test=coverage

* add dygraph test;test=coverage

* format;test=cpu,coverage

* format;test=cpu

* add api compat;test=cpu

* add cpu test

* rename

* rename

* fix

* fix test

* format

* eigen cpu

* eigen gpu grad pass

* cuda gpu pass

* format

* fix ci

* fix paddle.optimizer test=document_fix

* fix paddle.optimizer test=document_fix

* fix bugs in paddle.nn.functional document test=document_fix

* fix bugs in paddle.nn.functional document test=document_fix

* fix bugs in paddle.nn.functional document test=document_fix

* fix bugs in paddle.nn.functional document test=document_fix

* fix nn formula bugs test=document_fix

* fix nn formula bugs test=document_fix

* fix nn formula bugs test=document_fix

add __all__=[] to python files not in API public list; import * only support in API public list files (#32643)

* update 2.0 public api in nn

* replace Chinese character cause error in ci;synchronization with pr:#32588 to avoid 'ascii' codec in python2

* numbers used in paddle.nn.functional.norm but not imported

* add norm_by_times param to ctc_loss

* fix doc,test=develop

* add deprecated for softmax_with_cross_entropy, test=develop

* test for deprecated in english doc, test=develop

* test deprecated for softmax_with_cross_entropy in english doc, test=develop

* fix readme and English doc for cross_entropy, test=develop

* rm test for softmax_with_cross_entropy deprecated, test=develop

* update readme for CrossEntropyLoss, test=develop

* fix readme format, test=develop

* fix readme format, test=develop

* fix readme format for cross_entropy, test=develop

* add softmax_switch and fix softlabel for cross_entropy, test=develop

* 1)recovery softmax_with_cross_entropy in fluid 2) change softmax_switch to use_softmax 3) add example for softlabel for cross_entropy, test=develop

* fix Example number for cross_entropy, test=develop

* fix code format, test=develop

* fix for CI-Coverage, test=develop

* fix for CI-Coverage, test=develop

* fix ci-coverage for Non-ASCII character '\xe2' in file, test=develop

* fix ci-coverage for Non-ASCII character '\xe2' in nn.layer.loss.py, test=develop

* update description for doc when use_softmax=Fasle, test=develop

* fix some docs and code example for cross_entropy, test=develop

* delete redundant description for soft_label parameter of cross_entropy, test=develop

* fix some comment for test_cross_entropy_loss.py, test=develop

* fix code bugs

* fix code bugs test=document_fix

* fix code bugs test=document_fix

* fix nll_loss doc;test=document_fix;

* remove numpy and set_device;test=document_fix;

* remove numpy;test=document_fix;

* fix doc example, test=develop, test=document_fix

Fix ops doc for some ops 

* save one name in cross_entropy and softmax_cross_entropy, test=develop

* change used function in CrossEntropy from softmax_cross_entropy to cross_entropy, test=develop

* add soft_label and axis for CrossEntropyLoss and improve performance,test=develop

* fix conflict in nn/functional/loss.py, test=develop

* upgrade comment string to raw string

* fix string in

* fix string with ' '

* revert update on comments

* upgrade only necessary

* fix sample code checker

* fix comments with '''

* refine doc of bernoulli

* fix some problems

* fix unsqueeze

* fix squeeze

* fix doc

* fix English doc for dice_loss, log_loss, unfold and NLLLoss API test=document_fix

also fix `no_grad` alias

modified sample code of CTCLoss & ctc_loss by remove disable_static() & print([.*].numpy()) & alias, test=document_fix (#28403)

* add float64 input to ctc_loss

* modified error message of  warpctc

* update repo and tag of warpctc

* add test for warpctc with float64 input

* modified warpctc.cmake to make sure build always

* resolved sample code bug of warpctc

* add core.ops in warpctc dygraph

* fix a bug of test

* fix summary rnn

* fix kl_div bug when input shape is [1] and reduction is batchmean

fix doc, use to_tensor for the loss ops

* fix bug

* add version check

* fix docs, test=document_fix

* fix formula, test=document_fix

* add binary cross entropy with logit loss

* add functional ctc_loss and CTCLoss class.

* modified docstring of ctc_loss and CTCLoss

* add cross_entropy to nn/layer and nn/functional, test=develop

* use functional/cross_entropy in layer/CrossEntropy

* use functional/cross_entropy in layer/CrossEntropy, test=develop

Fix the API of bce loss and add functional API binary_cross_entropy 

add nn.functional.normalize API for API2.0, fix L1Loss API typo, test=develop

* upate the target to label, test=develop

* Update the code for the margin_ranking_loss, test=develop

* add Class KLDivLoss and function kl_div

add the api and doc for the margin_ranking_loss and MarginRankingLoss