function?[J?grad]?=?CostFunction（theta_params?input_layer_size?hidden_layer_size?class_num?X?y?lambda）

Theta_input?=?reshape（theta_params（1:hidden_layer_size?*?（input_layer_size?+?1））?hidden_layer_size?（input_layer_size?+?1））;
Theta_hidden?=?reshape（theta_params（（1?+?（hidden_layer_size?*?（input_layer_size?+?1）））:end）?class_num?（hidden_layer_size?+?1））;
m?=?size（X?1）;??????????????????????????????%??獲取樣本長度
J?=?0;???????????????????????????????????????%??初始化損失能量為0
input_grad?=?zeros（size（Theta_input））;???????%??初始化輸入層參數
hidden_grad?=?zeros（size（Theta_hidden））;?????%??初始化隱藏層參數

%-----------------------------one-hot處理-----------------------------------
%?1?=?[1?0?0?0?0?0?0?0?0?0]
%?2?=?[0?1?0?0?0?0?0?0?0?0]
%?3?=?[0?0?1?0?0?0?0?0?0?0]
%?4?=?[0?0?0?1?0?0?0?0?0?0]
%?5?=?[0?0?0?0?1?0?0?0?0?0]
%?6?=?[0?0?0?0?0?1?0?0?0?0]
%?7?=?[0?0?0?0?0?0?1?0?0?0]
%?8?=?[0?0?0?0?0?0?0?1?0?0]
%?9?=?[0?0?0?0?0?0?0?0?1?0]
%?0?=?[0?0?0?0?0?0?0?0?0?1]
%--------------------------------------------------------------------------
Y=[];
E?=?eye（class_num）;
for?i=1:class_num
????index?=?find（y==i）;
????Y（index:）?=?repmat（E（i:）size（index1）1）;
end
%--------------------------------------------------------------------------

%--------------------------------計算前向傳輸--------------------------------
X?=?[ones（m?1）?X];
hidden_return?=?sigmoid（X?*?Theta_input‘）;????????????????%?第二層（隱藏層）激活函數輸出
hidden_return?=?[ones（m?1）?hidden_return];??????????%
output?=?sigmoid（hidden_return?*?Theta_hidden‘）;%?輸出層激活函數輸出

temp1?=?[zeros（size（Theta_input1）1）?Theta_input（:2:end）];???%?常數項不參與正則化
temp2?=?[zeros（size（Theta_hidden1）1）?Theta_hidden（:2:end）];???%?常數項不參與正則化
temp1?=?sum（temp1?.^2）;?temp2?=?sum（temp2?.^2）;??????%?計算每個參數的平方和
cost?=?Y?.*?log（output）?+?（1?-?Y?）?.*?log（?（1?-?output））;???????????%?計算損失成本函數值
J?=?-1?/?m?*?sum（cost（:））?+?lambda/（2*m）?*?（?sum（temp1（:））+?sum（temp2（:））?）;

delta_1?=?zeros（size（Theta_input））;
delta_2?=?zeros（size（Theta_hidden））;

for?t?=?1:m
????inputdata?=?X（t:）‘;???????????????????????????????????%?獲取像素值
????hidden_input?=?Theta_input?*?inputdata;????????????????%?計算隱藏層輸入值
????hidden_output?=?sigmoid（hidden_input）;?????????????????%?計算隱藏層輸出值
????hidden_output?=?[1?;?hidden_output];???????????????????%?隱藏層增加常數項
????output_input?=?Theta_hidden?*?hidden_output;???????????%?計算輸出層輸入值
????output_output?=?sigmoid（output_input）;?????????????????%?計算輸出層輸出值
????err_output?=?zeros（class_num1）;???????????????????????%?構建輸出層誤差
%?????for?k?=?1:class_num
%?????????err_output（k）?=?output_output（k）?-?（y（t）?==?k）;????%?每類別輸出層誤差
%?????end
????err_output=output_output-Y（t:）‘;
????hidden_err?=?Theta_hidden‘?*?err_output;????????????????%?隱藏層誤差
????hidden_err?=?hidden_err（2:end）?.*?sigmoidGradient（hidden_input）;?%?隱藏層誤差
????delta_2?=?delta_2?+?err_output?*?hidden_output‘;
????delta_1?=?delta_1?+?hidden_err?*?inputdata‘;
end
Theta_input_temp?=?[zeros（size（Theta_input1）1）?Theta_input（:2:end）];
Theta_hidden_temp?=?[zeros（size（Theta_hidden1）1）?Theta_hidden（:2:end）];
in

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件???????6148??2017-12-21?09:52??Neural?Networks\.DS_Store

?????文件???????3408??2018-01-20?15:54??Neural?Networks\CostFunction.m

?????文件???????2753??2018-01-20?23:21??Neural?Networks\CostFunctionEx.m

?????文件???18453870??2017-12-21?09:52??Neural?Networks\datas\Data.mat

?????文件????7511764??2017-12-21?09:52??Neural?Networks\datas\MNIST.mat

?????文件???????3727??2017-12-21?09:52??Neural?Networks\fmin_theta.m

?????文件???????1540??2018-01-20?23:23??Neural?Networks\main.m

?????文件????????943??2018-01-20?23:01??Neural?Networks\mainEx.m

?????文件???????2942??2017-12-21?09:52??Neural?Networks\my-image\2.jpeg

?????文件???????3226??2017-12-21?09:52??Neural?Networks\my-image\5.jpeg

?????文件???????2079??2017-12-21?09:52??Neural?Networks\my-image\7.jpeg

?????文件????????646??2017-12-21?09:52??Neural?Networks\num2test.m

?????文件????????423??2017-12-21?09:59??Neural?Networks\online_test.m

?????文件????????793??2017-12-21?09:52??Neural?Networks\plotnumData.m

?????文件????????585??2017-12-21?09:52??Neural?Networks\predict.m

?????文件????????114??2018-01-18?21:06??Neural?Networks\randWeights.m

?????文件????????183??2018-01-18?21:12??Neural?Networks\randWeightsEx.m

?????文件?????????56??2017-12-21?09:52??Neural?Networks\sigmoid.m

?????文件?????????92??2017-12-21?09:52??Neural?Networks\sigmoidGradient.m

?????目錄??????????0??2017-12-21?09:52??Neural?Networks\datas

?????目錄??????????0??2017-12-21?09:52??Neural?Networks\my-image

?????目錄??????????0??2018-01-20?23:30??Neural?Networks

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

?????????????25995292????????????????????22