Tensorflow2.0 entry and practical study notes (1, 2)-optimization function, learning rate, back propagation

table of Contents

Theoretical knowledge

1.1 Multilayer Perceptron

1.2 Gradient descent method

1.3 Learning rate-hyperparameter (manually configurable)

1.4 Backpropagation algorithm

1.5 Optimization function

RMSprop

1.6 Network optimization and hyperparameter selection

1.6.1 How to choose hyperparameters

Use dropout to prevent overfitting

Why is it said that Dropout can solve overfitting?

1.7 Actual combat


Theoretical knowledge

1.1 Multilayer perceptron

1.2 Gradient descent method

1.3 Learning rate-hyperparameter (manually configurable)

Inappropriate learning rate

Local extreme point

1.4 Backpropagation algorithm

1.5 Optimization function

  • SGD stochastic gradient
  • adam optimizer

Common parameters

RMSprop

Code

1.6 Network optimization and hyperparameter selection

1.6.1 How to choose hyperparameters

So how to improve the fitting ability of the network

Note:
The number of neurons in a single layer should not be too small. If it is too small, it will cause an information bottleneck and make the model underfit

13W trainable parameters

Result improved

 

Judging from the correct rate

  • Underfitting: test and training data scores are low
  • Overfitting : The score is relatively low on the test data, and the score on the training data is compared

Use dropout to prevent overfitting

Random forest and ensemble methods

Mentioned in the AlexNet paper

Why is it said that Dropout can solve overfitting?

Preferences

Therefore, our parameter training principle

Then, suppress overfitting---no problem in capacity

Inhibits fit most good way is to increase the training data

Tuning parameters-experience

General principles of network construction

General principle: ensure that the neural network capacity is sufficient to fit the data

1. Increase the network capacity until overfitting

Second, take measures to suppress over-fitting

3. Continue to increase network capacity until overfitting

1.7 Actual combat

How to add droupout layer to the network

Reducing the network size is also a way

 

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Origin blog.csdn.net/qq_37457202/article/details/107761309