Hi,

Trying to implement the model() function for exercise 4, but I’m receiving an index error: list index out of range in the rnn_forward function when I run my cells for exercise 4.

Here’s the output with my code censored with ‘<myCode>’.

```
j = 0 idx = 0
single_example = turiasaurus
single_example_chars ['t', 'u', 'r', 'i', 'a', 's', 'a', 'u', 'r', 'u', 's']
single_example_ix [20, 21, 18, 9, 1, 19, 1, 21, 18, 21, 19]
X = [None, 20, 21, 18, 9, 1, 19, 1, 21, 18, 21, 19]
Y = [20, 21, 18, 9, 1, 19, 1, 21, 18, 21, 19, 0]
Iteration: 0, Loss: 23.087336
Nkzxwtdmfqoeyhsqwasjkjvu
Kneb
Kzxwtdmfqoeyhsqwasjkjvu
Neb
Zxwtdmfqoeyhsqwasjkjvu
Eb
Xwtdmfqoeyhsqwasjkjvu
---------------------------------------------------------------------------
IndexError Traceback (most recent call last)
<ipython-input-12-725c093d6b91> in <module>
----> 1 parameters, last_name = model(data.split("\n"), ix_to_char, char_to_ix, 22001, verbose = True)
2
3 assert last_name == 'Trodonosaurus\n', "Wrong expected output"
4 print("\033[92mAll tests passed!")
<ipython-input-11-1dca6d0b0775> in model(data_x, ix_to_char, char_to_ix, num_iterations, n_a, dino_names, vocab_size, verbose)
61 # Perform one optimization step: Forward-prop -> Backward-prop -> Clip -> Update parameters
62 # Choose a learning rate of 0.01
---> 63 curr_loss, gradients, a_prev = <myCode>
64
65 ### END CODE HERE ###
<ipython-input-9-fca0aba78113> in optimize(X, Y, a_prev, parameters, learning_rate)
32
33 # Forward propagate through time (≈1 line)
---> 34 loss, cache = <myCode>
35
36 # Backpropagate through time (≈1 line)
~/work/W1A2/utils.py in rnn_forward(X, Y, a0, parameters, vocab_size)
100
101 # Update the loss by substracting the cross-entropy term of this time-step from it.
--> 102 loss -= np.log(y_hat[t][Y[t],0])
103
104 cache = (y_hat, a, x)
IndexError: list index out of range
```

I re-ran all the cells before this one and all the tests passed, so doubt there’s anything wrong with any of the prior functions.

I re-read all the steps and still can’t figure out why I’m receiving this index-out-of-range error. I assume Y[t] is the problem?

Any help would be much appreciated, thanks.