# Transpose sign for W Matrix

**URL:** <https://community.deeplearning.ai/t/transpose-sign-for-w-matrix/125667>\
**Category:** Neural Networks and Deep Learning\
**Tags:** coursera-platform\
**Created:** [May 6, 2022, 4:44pm UTC](https://community.deeplearning.ai/t/transpose-sign-for-w-matrix/125667 "2022-05-06T16:44:09Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Pouya\_Hosseinniya](https://avatars.discourse-cdn.com/v4/letter/p/f08c70/32.png) [@Pouya\_Hosseinniya](https://community.deeplearning.ai/u/Pouya_Hosseinniya)\
**Post date:** [May 6, 2022, 4:44pm UTC](https://community.deeplearning.ai/t/transpose-sign-for-w-matrix/125667/1 "2022-05-06T16:44:09Z")

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hi, i have a question, in lecture notes of the third week of course, why T(transpose sign) is not placed above of W matrix?

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**Author:** ![kenb](https://sea1.discourse-cdn.com/dlai/user_avatar/community.deeplearning.ai/kenb/32/69_2.png) [@kenb](https://community.deeplearning.ai/u/kenb)\
**Post date:** [May 6, 2022, 5:13pm UTC](https://community.deeplearning.ai/t/transpose-sign-for-w-matrix/125667/2 "2022-05-06T17:13:30Z")

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Hi, @Pouya_Hosseinniya. Although I am not sure what you’re looking at, the accepted mathematical notation uses a `T` or prime (\prime) superscripted on the matrix that is to be transposed: X^T or X^\prime, for example. In this course, the `T`-notation is used.

If you are referring to the computational analogue in Python/NumPy, then we have `X.T`.

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**Author:** ![paulinpaloalto](https://sea1.discourse-cdn.com/dlai/user_avatar/community.deeplearning.ai/paulinpaloalto/32/187_2.png) [@paulinpaloalto](https://community.deeplearning.ai/u/paulinpaloalto)\
**Post date:** [May 6, 2022, 5:13pm UTC](https://community.deeplearning.ai/t/transpose-sign-for-w-matrix/125667/3 "2022-05-06T17:13:36Z")

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Because Prof Ng has defined the layout of the W matrix so that a transpose is no longer required. It is required in the Logistic Regression case only because he chooses to define the weight vector w as a column vector. Here’s [another recent post](https://community.deeplearning.ai/t/cant-understand-a-matrix/125234/2) that talks about this in more detail.

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**Author:** ![Pouya\_Hosseinniya](https://avatars.discourse-cdn.com/v4/letter/p/f08c70/32.png) [@Pouya\_Hosseinniya](https://community.deeplearning.ai/u/Pouya_Hosseinniya)\
**Post date:** [May 7, 2022, 6:58am UTC](https://community.deeplearning.ai/t/transpose-sign-for-w-matrix/125667/4 "2022-05-07T06:58:20Z")

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thanks

 ![image](https://global.discourse-cdn.com/dlai/original/3X/3/b/3bdb657ae5361376f2fdf312a9d2b8eb46851693.jpeg)  
my question is that in the picture that i uploaded the W\[1\].T has not used and only W\[2\] has been written here. why?

* * *

1. 1 

2. 1

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**Author:** ![Pouya\_Hosseinniya](https://avatars.discourse-cdn.com/v4/letter/p/f08c70/32.png) [@Pouya\_Hosseinniya](https://community.deeplearning.ai/u/Pouya_Hosseinniya)\
**Post date:** [May 7, 2022, 6:59am UTC](https://community.deeplearning.ai/t/transpose-sign-for-w-matrix/125667/5 "2022-05-07T06:59:48Z")

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thank you for your help.