Your gradient_check_n() function has an error. It doesnâ€™t return the correct results for one of the tests that are in gradient_check_n_test_case().

You can find this test function in one of the .py files that are imported in Cell 1 in the notebook. These files can be inspected via the File menu.

Getting 1.0 as the answer most likely means youâ€™ve made a mistake in the final difference calculation. Please carefully examine the math formula there and then compare that to your code. One other thing to check is to note that `grad`

and `gradapprox`

in that formula are vectors, not individual elements of vectors, right?

Sir I examined my difference code against the mathematical formula but still I have the error. what should i do next?

One common mistake is student copy code from `theta_plus[i]`

and paste it to `theta_minus[i]`

without changing the sign.

Itâ€™s probably time to just look at your code. Please see your DMs for a message from me about how to proceed with that.

To close the loop on the public thread, the error is a classic â€ścopy/pasteâ€ť error. The `theta_minus`

code was copied from the `theta_plus`

, but not changed. So `gradapprox`

ends up as all zeros, which is why the difference value ends up as 1.0.