Week 2 Exercise 3 Wrong values . Check you formulas for parameters['W1']

Course Q&A Deep Learning Specialization Improving Deep Neural Networks: Hyperparameter tun
1

Good day. In update_parameters_with_adam I got the result:

W1 = 
[[ 1.63980554 -0.62720906 -0.5436752 ]
 [-1.088665    0.84990399 -2.28595842]]
W2 = 
[[ 0.33513168 -0.26504361  1.47768455]
 [-2.04432584 -0.30683853 -0.36853489]
 [ 1.14935566 -1.27961162 -0.15697095]]
b1 = 
[[ 1.76200086]
 [-0.74571222]]
b2 = 
[[-0.8940762 ]
 [ 0.02681914]
 [ 0.56726001]]
---------------------------------------------------------------------------
AssertionError                            Traceback (most recent call last)
<ipython-input-50-99ca62433443> in <module>
      7 print(f"b2 = \n{parameters['b2']}")
      8 
----> 9 update_parameters_with_adam_test(update_parameters_with_adam)

~/work/release/W2A1/public_tests.py in update_parameters_with_adam_test(target)
    261         assert type(parameters[key]) == np.ndarray, f"Wrong type for parameters['{key}']. Expected np.ndarray"
    262         assert parameters[key].shape == parametersi[key].shape, f"Wrong shape for  parameters['{key}']. The update must keep the dimensions of parameters inputs"
--> 263         assert np.allclose(parameters[key][0], expected_parameters[key]), f"Wrong values. Check you formulas for parameters['{key}']"
    264         #print(f"{key}: \n {str(parameters[key])}")
    265 

AssertionError: Wrong values. Check you formulas for parameters['W1']

This result differs by thousandths from the result of the test task. What could be wrong?

Thank you for your time

2

Hey @plohih_love,
It would be a little difficult for us to figure out the exact issue from this error stack. Can you please DM me your implementation for the update_parameters_with_adam function?

Cheers,
Elemento

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3

Please note that a difference in the 3rd decimal place is not a rounding error: it’s a real mistake. We’re dealing with 64 bit floating point values here, so rounding errors are of the order of 10^{-16}.

The most common problems here have to do with “order of operations”. Please check your code and note that the \epsilon value in the formula is in the denominator, but not under the square root, right?

2 Likes
4

Thanks everyone. I subtracted ϵ, not added :woman_facepalming:

1 Like