kai

Programming Machine Learning:

Programming Machine Learning
From Coding to Deep Learning
German edition

Chapter 11
Training the network
Page 191

def back(X, Y, y_hat, w2, h):
w2_gradient = np.matmul(prepend_bias(h).T, y_hat - Y) / X.shape[0]

 a_gradient = np.matmul(y_hat - Y, w2[1:].T) * sigmoid_gradient(h)
 w1_gradient = np.matmul(prepend_bias(X).T, a_gradient) / X.shape[0]

 return (w1_gradient, w2_gradient)

Hi Paolo,
can you explain me how to come to the decision to multiply this expression:
np.matmul(y_hat - Y, w2[1:].T) * sigmoid_gradient(h)
element by element?

Sincerely,
Kai

4 comments

#question /book-programming-machine-learning

1 553 4

2023-10-03 20:36:18 UTC

Most Liked

kai

As I understand it, there is no recipe to derive compositions of functions, whose inputs are matrices, according to them, as it is the case with a scalar.

Thank you for giving me an answer that helped my understanding anyway.

I am fascinated by mathematics and its power. But to be able to see its beauty, it requires a lot of time. That is why I asked such a question.

Your book was recommended to me and declared very worthwhile, which I can confirm 100%. It is my introduction to ML. Thank you for it!

Translated with DeepL Translate: The world's most accurate translator (free version)

Post #5

Where Next?

View thread on forum

View Programming Machine Learning's book portal

Post errata for this book

Post a suggestion for this book

Post a question about this book

Post a review about this book

question

Home PragProg Customers

#question /book-programming-machine-learning

1 553 4

Last post

Popular Pragmatic Bookshelf topics

PragProg Customers

Distributed Services With Go - Ch 3 index errors on Config

In Chapter 3, the source for index introduces Config on page 31, followed by more code including tests; Config isn’t introduced until pag...

#pragprog #errata /book-distributed-services-with-go

8 1316 3

2021-04-08 12:48:40 UTC

New

PragProg Customers

Effective Testing with RSpec 3: Running Sequel migrations fails (page 84)

Following the steps described in Chapter 6 of the book, I’m stuck with running the migration as described on page 84: bundle exec sequel...

#errata /book-effective-testing-with-rspec-3

4 1152 1

2020-07-16 15:18:25 UTC

New

PragProg Customers

Programming Phoenix LiveView: errata and remarks Version B2.0

The generated iex result below should list products instead of product for the metadata. (page 67) iex> product = %Product{} %Pento....

#errata /book-programming-phoenix-liveview

0 1800 20

2021-03-23 10:33:03 UTC

New

PragProg Customers

Modern CSS with Tailwind: setting up Rails app

In case this helps anyone, I’ve had issues setting up the rails source code. Here were the solutions: In Gemfile, change gem 'rails' t...

#errata /book-modern-css-with-tailwind

3 1278 2

2022-01-05 00:19:21 UTC

New

PragProg Customers

A Common-Sense Guide to Data Structures and Algorithms, Second Edition: (pg460)

Hello! Thanks for the great book. I was attempting the Trie (chap 17) exercises and for number 4 the solution provided for the autocorre...

#errata /book-a-common-sense-guide-to-data-structures-and-algorithms-second-edition

0 1157 3

2023-03-10 05:02:03 UTC

New

PragProg Customers

Kotlin and Android Development featuring Jetpack: $kotlin_version ? (page 8)

I’m running Android Studio “Arctic Fox” 2020.3.1 Patch 2, and I’m embarrassed to admit that I only made it to page 8 before running into ...

#errata /book-kotlin-and-android-development-featuring-jetpack

0 1698 3

2021-09-03 21:44:18 UTC

New

PragProg Customers

Programming Phoenix LiveView: live_modal/2 instead of live_component/3 (210)

“The ProductLive.Index template calls a helper function, live_component/3, that in turn calls on the modal component. ” Excerpt From: Br...

#errata /book-programming-phoenix-liveview

3 1042 6

2021-11-03 12:30:33 UTC

New

PragProg Customers

Powerful Command-Line Applications in Go: Exercise Solutions (many pages)

Is there any place where we can discuss the solutions to some of the exercises? I can figure most of them out, but am having trouble with...

#question /book-powerful-command-line-applications-in-go

17 1396 9

2022-02-09 15:00:31 UTC

New

PragProg Customers

Agile Web Development with Rails 7: page 113 - Seeing the list of products

I’m a newbie to Rails 7 and have hit an issue with the bin/Dev script mentioned on pages 112-113. Iteration A1 - Seeing the list of prod...

#question /book-agile-web-development-with-rails-7

0 2631 9

2024-01-06 20:36:27 UTC

New

PragProg Customers

Programming Phoenix LiveView: B6.0 pg 56 - current-user not set

It seems the second code snippet is missing the code to set the current_user: current_user: Accounts.get_user_by_session_token(session["...

#errata /book-programming-phoenix-liveview

0 1898 8

2023-01-11 03:06:26 UTC

New

Other popular topics

General Dev>Hardware

Which keyboard do you have?

If it’s a mechanical keyboard, which switches do you have? Would you recommend it? Why? What will your next keyboard be? Pics always w...

#hardware /keyboards #sticky #mechanical-keyboards

144 9115 50

2021-01-07 23:58:36 UTC

New

Backend>Chat

What is the reason behind Rust’s web framework, Rocket, not performing as well as expected in the Techempower benchmarks?

I know that these benchmarks might not be the exact picture of real-world scenario, but still I expect a Rust web framework performing a ...

#web-frameworks /rust

36 7463 11

2020-06-21 10:50:02 UTC

New

General Dev>Hardware

Moonlander Keyboard (Mechanical) (Ergonomic) (Split) (Ortholinear)

Bought the Moonlander mechanical keyboard. Cherry Brown MX switches. Arms and wrists have been hurting enough that it’s time I did someth...

#hardware /keyboards #moonlander #mechanical-keyboards #ortholinear #ergonomic

212 17779 90

2021-07-13 15:33:55 UTC

New

General Dev>Dev Chat

Languages Without Garbage Collection

Continuing the discussion from Thinking about learning Crystal, let’s discuss - I was wondering which languages don’t GC - maybe we can c...

#garbage-collection

21 5575 7

2021-05-06 05:54:58 UTC

New

Backend>Learning Resources

Python Testing with pytest, Second Edition

Create efficient, elegant software tests in pytest, Python's most powerful testing framework. Brian Okken @brianokken Edited by Kat...

pragprog.com

#pragprog /python #published-book /book-python-testing-with-pytest-second-edition

16 7461 4

2021-06-25 16:57:39 UTC

New

Community>In The Spotlight

Spotlight: Rebecca Skinner (Author) Interview and AMA!

Author Spotlight Rebecca Skinner @RebeccaSkinner Welcome to our latest author spotlight, where we sit down with Rebecca Skinner, auth...

#author-spotlight /haskell /book-effective-haskell

106 11719 28

2022-11-16 10:29:37 UTC

New

Community>In The Spotlight

Spotlight: VM Brasseur (Author) Interview and AMA!

Author Spotlight: VM Brasseur @vmbrasseur We have a treat for you today! We turn the spotlight onto Open Source as we sit down with V...

#author-spotlight /book-forge-your-future-with-open-source

16 5051 11

2023-03-27 16:00:12 UTC

New

Game Dev>Questions

I want to learn how make a game, but where should I start?

I’m able to do the “artistic” part of game-development; character designing/modeling, music, environment modeling, etc. However, I don’t...

#game-dev

15 4965 9

2025-10-18 13:12:58 UTC

New

AI>In The News

DeepSeek (671B) running on a cluster of 8 Mac Mini Pros with 64GB RAM each

This is cool! DEEPSEEK-V3 ON M4 MAC: BLAZING FAST INFERENCE ON APPLE SILICON We just witnessed something incredible: the largest open-s...

#ai #macs /deepseek

0 6695 1

2025-01-29 18:43:37 UTC

New

Backend>Learning Resources

Simplicity

Fight complexity and reclaim the original spirit of agility by learning to simplify how you develop software. The result: a more humane a...

pragprog.com

#pragprog #published-book /book-simplicity

10 6553 8

2025-03-14 21:53:12 UTC

New

Programming Machine Learning:

kai

Programming Machine Learning:

Most Liked

kai

Where Next?

Popular Pragmatic Bookshelf topics

Distributed Services With Go - Ch 3 index errors on Config

Effective Testing with RSpec 3: Running Sequel migrations fails (page 84)

Programming Phoenix LiveView: errata and remarks Version B2.0

Modern CSS with Tailwind: setting up Rails app

A Common-Sense Guide to Data Structures and Algorithms, Second Edition: (pg460)

Kotlin and Android Development featuring Jetpack: $kotlin_version ? (page 8)

Programming Phoenix LiveView: live_modal/2 instead of live_component/3 (210)

Powerful Command-Line Applications in Go: Exercise Solutions (many pages)

Agile Web Development with Rails 7: page 113 - Seeing the list of products

Programming Phoenix LiveView: B6.0 pg 56 - current-user not set