# Ex 4 and 5 nlp course 2 assignment 4 of week 4 **URL:** \ **Category:** NLP with Probabilistic Models\ **Tags:** week-module-4\ **Created:** [April 6, 2023, 6:48pm UTC](https://community.deeplearning.ai/t/ex-4-and-5-nlp-course-2-assignment-4-of-week-4/304379 "2023-04-06T18:48:06Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Mahnoor\_Shafiq](https://avatars.discourse-cdn.com/v4/letter/m/ecc23a/32.png) [@Mahnoor\_Shafiq](https://community.deeplearning.ai/u/Mahnoor_Shafiq)\ **Post date:** [April 6, 2023, 6:48pm UTC](https://community.deeplearning.ai/t/ex-4-and-5-nlp-course-2-assignment-4-of-week-4/304379/1 "2023-04-06T18:48:06Z")
Hi @Mubsi , Lab id: jfxmpusrcheo Can anyone please help me with exercises 4 and 5? I tried many times but did not get the solution. I will appreciate your help and support. ---
**Author:** ![Elemento](https://sea1.discourse-cdn.com/dlai/user_avatar/community.deeplearning.ai/elemento/32/854_2.png) [@Elemento](https://community.deeplearning.ai/u/Elemento)\ **Post date:** [April 7, 2023, 5:24am UTC](https://community.deeplearning.ai/t/ex-4-and-5-nlp-course-2-assignment-4-of-week-4/304379/2 "2023-04-07T05:24:02Z")
Hey @Mahnoor_Shafiq, Can you please share your error stack, or in other words, the error that you are getting, in exercises 4 and 5? Cheers, Elemento ---
**Author:** ![Mahnoor\_Shafiq](https://avatars.discourse-cdn.com/v4/letter/m/ecc23a/32.png) [@Mahnoor\_Shafiq](https://community.deeplearning.ai/u/Mahnoor_Shafiq)\ **Post date:** [April 7, 2023, 2:44pm UTC](https://community.deeplearning.ai/t/ex-4-and-5-nlp-course-2-assignment-4-of-week-4/304379/3 "2023-04-07T14:44:04Z")
Hi, Attached below is the error. ![image](https://global.discourse-cdn.com/dlai/original/3X/6/0/608ed88b22ba0a8f7c89d73114355fc68479871a.png) ---
**Author:** ![Mahnoor\_Shafiq](https://avatars.discourse-cdn.com/v4/letter/m/ecc23a/32.png) [@Mahnoor\_Shafiq](https://community.deeplearning.ai/u/Mahnoor_Shafiq)\ **Post date:** [April 7, 2023, 3:20pm UTC](https://community.deeplearning.ai/t/ex-4-and-5-nlp-course-2-assignment-4-of-week-4/304379/4 "2023-04-07T15:20:52Z")
Wrong output values for gradient of b1 vector. Expected: [[0.56665732] [0.46268776] [0.10631469] [0.] [0.11041817] [0.32025188] [0.] [0.08430877] [0.19341] [0.08339139] [0.] [0.] [0.19055422] [0.56405984] [0.13321987]] Got: [[0.] [0.] [0.] [0.] [0.] [0.] [0.] [0.] [0.] [0.] [0.] [0.] [0.] [0.] [0.]]. Wrong output values for gradient of b2 vector. Expected: [[0.09488382] [-0.92645217] [0.04061033] [0.11081115] [0.06029008] [0.15000559] [0.12740163] [0.14957542] [0.1007054] [0.09216876]] Got: [[0.70541249] [-6.88769622] [0.30191695] [0.82382401] [0.44822579] [1.11521454] [0.94716571] [1.11201645] [0.74869294] [0.68522741]]. Wrong output values for gradient of b1 vector. Expected: [[0.01864644] [0.] [0.] [0.] [0.] [0.14815984] [0.25794505] [0.24893135] [0.05895103] [0.]] Got: [[0.] [0.] [0.] [0.] [0.] [0.] [0.] [0.] [0.] [0.]]. Wrong output values for gradient of b2 vector. Expected: [[0.22636192] [-0.59052847] [0.12268763] [0.06530444] [0.17617448]] Got: [[1.30236687] [-3.39758876] [0.70587979] [0.37572724] [1.01361486]]. 12 Tests passed 4 Tests failed After some changes now I am getting this error. ---
**Author:** ![Mahnoor\_Shafiq](https://avatars.discourse-cdn.com/v4/letter/m/ecc23a/32.png) [@Mahnoor\_Shafiq](https://community.deeplearning.ai/u/Mahnoor_Shafiq)\ **Post date:** [April 7, 2023, 8:41pm UTC](https://community.deeplearning.ai/t/ex-4-and-5-nlp-course-2-assignment-4-of-week-4/304379/5 "2023-04-07T20:41:56Z")
Can you please help me with this? ---
**Author:** ![Elemento](https://sea1.discourse-cdn.com/dlai/user_avatar/community.deeplearning.ai/elemento/32/854_2.png) [@Elemento](https://community.deeplearning.ai/u/Elemento)\ **Post date:** [April 8, 2023, 6:01am UTC](https://community.deeplearning.ai/t/ex-4-and-5-nlp-course-2-assignment-4-of-week-4/304379/6 "2023-04-08T06:01:11Z")
Hey @Mahnoor_Shafiq, Did you cross-check your equations with the ones given in the lecture video? Let me give you some starting hints. For computing `grad_b1`, as per the equations given, we don’t need W\_1, still in your code, I can see that you have used it. Similarly, for computing `grad_b2`, I can see that you have used H^T, still it’s not used in the equations given. Re-check your equations once using the ones given in this [lecture video](https://www.coursera.org/learn/probabilistic-models-in-nlp/lecture/mPJwt/training-a-cbow-model-backpropagation-and-gradient-descent) as a reference. Let us know if this helps. Cheers, Elemento ---
**Author:** ![Mahnoor\_Shafiq](https://avatars.discourse-cdn.com/v4/letter/m/ecc23a/32.png) [@Mahnoor\_Shafiq](https://community.deeplearning.ai/u/Mahnoor_Shafiq)\ **Post date:** [April 9, 2023, 10:18pm UTC](https://community.deeplearning.ai/t/ex-4-and-5-nlp-course-2-assignment-4-of-week-4/304379/7 "2023-04-09T22:18:01Z")
Hi, Hope you are doing well. Sorry for the late response. Thank you for your help I checked the lecture and I was able to solve the issue. Thank you for your help again. ---
**Author:** ![sunbird](https://avatars.discourse-cdn.com/v4/letter/s/8797f3/32.png) [@sunbird](https://community.deeplearning.ai/u/sunbird)\ **Post date:** [October 8, 2023, 6:40pm UTC](https://community.deeplearning.ai/t/ex-4-and-5-nlp-course-2-assignment-4-of-week-4/304379/8 "2023-10-08T18:40:41Z")
> [@Elemento](#): > > lecture video Hi @Elemento I’m also stuck on this issue. Could you please advise me on what the ‘step’ function implies here: ![Screenshot 2023-10-08 at 11.43.42 PM](https://global.discourse-cdn.com/dlai/original/3X/6/d/6df1352143b717f9dabb28d6ecfdfaa32f96ba00.jpeg) ---
**Author:** ![sunbird](https://avatars.discourse-cdn.com/v4/letter/s/8797f3/32.png) [@sunbird](https://community.deeplearning.ai/u/sunbird)\ **Post date:** [October 9, 2023, 3:52am UTC](https://community.deeplearning.ai/t/ex-4-and-5-nlp-course-2-assignment-4-of-week-4/304379/9 "2023-10-09T03:52:27Z")
Also, the formula for gradient of b2 is missing in the slide in the latest version of the video. I could not find it in the lecture notes as well.