# W3_A1_Ex-6_AssertionError_Getting wrong values

Exercise 6. Backward Propagation
Following errors are thrown eventhough the output values match with the expected values.

## dW1 = [[ 0.00301023 -0.00747267] [ 0.00257968 -0.00641288] [-0.00156892 0.003893 ] [-0.00652037 0.01618243]] db1 = [[ 0.00176201] [ 0.00150995] [-0.00091736] [-0.00381422]] dW2 = [[ 0.00078841 0.01765429 -0.00084166 -0.01022527]] db2 = [[-0.16655712]]

AssertionError Traceback (most recent call last)
in
7 print ("db2 = "+ str(grads[“db2”]))
8
----> 9 backward_propagation_test(backward_propagation)

~/work/release/W3A1/public_tests.py in backward_propagation_test(target)
187 assert output[“db2”].shape == expected_output[“db2”].shape, f"Wrong shape for db2."
188
→ 189 assert np.allclose(output[“dW1”], expected_output[“dW1”]), “Wrong values for dW1”
190 assert np.allclose(output[“db1”], expected_output[“db1”]), “Wrong values for db1”
191 assert np.allclose(output[“dW2”], expected_output[“dW2”]), “Wrong values for dW2”

AssertionError: Wrong values for dW1

Expected output

dW1 = [[ 0.00301023 -0.00747267]
[ 0.00257968 -0.00641288]
[-0.00156892 0.003893 ]
[-0.00652037 0.01618243]]
db1 = [[ 0.00176201]
[ 0.00150995]
[-0.00091736]
[-0.00381422]]
dW2 = [[ 0.00078841 0.01765429 -0.00084166 -0.01022527]]
db2 = [[-0.16655712]]
All tests passed!

It’s strange Try Kernel → Restart and Clear output, and then Run all cells again. Let me know if it doesn’t help.

I tried once. it didnt work

I even created a new file using file open and entered all the user code required. It didnt work

Please send me your code in a private message. Click my name and message.

PS: I will be back in 2 hrs.

To update others, while there are multiple ways (mathematically correct) to compute the dZ1, it is recommended to follow the instruction given to you in a Notebook:
“So you can compute g^{[1]'}(Z^{[1]}) using `(1 - np.power(A1, 2))`.”

We are already working on why other mathematically correct ways give errors.

The same problem persists.