I cannot get this code to work. please help.

Mon, 21 Mar 2022 05:59:53 +0000

from keras.models import Sequential
from keras.layers import Dense
from keras.layers import LSTM
from sklearn.model_selection import train_test_split

model = Sequential()
model.add(LSTM( 10, input_shape=(1, 1)))
model.add(Dense(1, activation="linear"))
model.compile(loss="mse", optimizer="adam")

X, y = get_data()

X_train, X_test, y_train, y_test = train_test_split(x, y, test_size=0.2, random_state=1)
X_train_2, X_val, y_train_2, y_val = train_test_split(X_train, y_train, test_size=0.25, random_state=1)

model.fit(X_train, y_train, epochs=800, validation_data=(X_val, y_val), shuffle=False)

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How to update the weights in backpropagation algorithm when activation function in not linear?

Mon, 10 Aug 2020 21:55:19 +0000

The goal of backpropagation is to optimize the weights so that the neural network can learn how to correctly map arbitrary inputs to outputs.

Assume for the following neural network, inputs = [$i_1,i_2$] = [0.05, 0.10], we want the neural network to output = [$o_1$,$o_2$] = [0.01, 0.99], and for learning rate, $\alpha=0.5$.
In addition, the activation function for the hidden layer (both $h_1$ and $h_2$) is sigmoid (logistic):

$S(x)=\frac{1}{1+e^{-x}}$

https://i.imgur.com/cnY5feu.png

Hint:
$w_{new} = w_{old} - \alpha \frac{\partial E}{\partial w}$

$E_{\text {total}}=\sum \frac{1}{2}(\text {target}-\text {output})^{2}$

a) Show step by step solution to calculate weights $w_1$ to $w_8$ after one update in table below.
b) Calculate initial error and error after one update (assume biases $[b_1,b_2]$ are not changing during the updates).

Updating weights in backpropagation algorithm
Weights	Initialization	New weights after one step
$w1$	0.15	?
$w2$	0.20	?
$w3$	0.25	?
$w4$	0.30	?
$w5$	0.40	?
$w6$	0.45	?
$w7$	0.50	?
$w8$	0.55	?

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I cannot get this code to work. please help.

How to update the weights in backpropagation algorithm when activation function in not linear?