import?numpy?as?np


def?sigmoid（Z）:
????“““
????Implements?the?sigmoid?activation?in?numpy

????Arguments:
????Z?--?numpy?array?of?any?shape

????Returns:
????A?--?output?of?sigmoid（z）?same?shape?as?Z
????cache?--?returns?Z?as?well?useful?during?backpropagation
????“““

????A?=?1?/?（1?+?np.exp（-Z））
????cache?=?Z

????return?A?cache


def?relu（Z）:
????“““
????Implement?the?RELU?function.

????Arguments:
????Z?--?Output?of?the?linear?layer?of?any?shape

????Returns:
????A?--?Post-activation?parameter?of?the?same?shape?as?Z
????cache?--?a?python?dictionary?containing?“A“?;?stored?for?computing?the?backward?pass?efficiently
????“““

????A?=?np.maximum（0?Z）

????assert?（A.shape?==?Z.shape）

????cache?=?Z
????return?A?cache


def?relu_backward（dA?cache）:
????“““
????Implement?the?backward?propagation?for?a?single?RELU?unit.

????Arguments:
????dA?--?post-activation?gradient?of?any?shape
????cache?--?‘Z‘?where?we?store?for?computing?backward?propagation?efficiently

????Returns:
????dZ?--?Gradient?of?the?cost?with?respect?to?Z
????“““

????Z?=?cache
????dZ?=?np.array（dA?copy=True）??#?just?converting?dz?to?a?correct?object.

????#?When?z?<=?0?you?should?set?dz?to?0?as?well.
????dZ[Z?<=?0]?=?0

????assert?（dZ.shape?==?Z.shape）

????return?dZ


def?sigmoid_backward（dA?cache）:
????“““
????Implement?the?backward?propagation?for?a?single?SIGMOID?unit.

????Arguments:
????dA?--?post-activation?gradient?of?any?shape
????cache?--?‘Z‘?where?we?store?for?computing?backward?propagation?efficiently

????Returns:
????dZ?--?Gradient?of?the?cost?with?respect?to?Z
????“““

????Z?=?cache

????s?=?1?/?（1?+?np.exp（-Z））
????dZ?=?dA?*?s?*?（1?-?s）

????assert?（dZ.shape?==?Z.shape）

????return?dZ

?屬性????????????大小?????日期????時(shí)間???名稱
-----------?---------??----------?-----??----

?????文件?????616958??2017-09-02?17:29??dnn_utils_v2_lr_utils_dataset\cat_datasets\test_catvnoncat.h5

?????文件????2572022??2017-09-02?17:30??dnn_utils_v2_lr_utils_dataset\cat_datasets\train_catvnoncat.h5

?????文件???????1795??2018-03-31?20:46??dnn_utils_v2_lr_utils_dataset\dnn_utils_v2.py

?????文件????????768??2018-03-31?10:48??dnn_utils_v2_lr_utils_dataset\lr_utils.py

?????目錄??????????0??2018-03-31?21:52??dnn_utils_v2_lr_utils_dataset\cat_datasets

?????目錄??????????0??2018-03-31?21:53??dnn_utils_v2_lr_utils_dataset

-----------?---------??----------?-----??----

??????????????3191543????????????????????6