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 - gogoproto on linux

page 20: … protoc command… I had to additionally run the following go get commands in order to be able to compile protobuf code using go...

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

14 2953 7

2020-10-16 05:21:10 UTC

New

PragProg Customers

Hands-On Rust: Wrong multiplier for 8x8 console in main.rs

Title: Hands-On Rust (Chap 8 (Adding a Heads Up Display) It looks like .with_simple_console_no_bg(SCREEN_WIDTH*2, SCREEN_HEIGHT*2...

#errata /book-hands-on-rust

9 2026 5

2022-02-15 14:09:12 UTC

New

PragProg Customers

The Cucumber for Java Book:

Hello! On page xix of the preface, it says there is a community forum "… for help if your’re stuck on one of the exercises in this book… ...

#question /book-the-cucumber-for-java-book

3 1143 1

2021-01-12 18:03:10 UTC

New

PragProg Customers

Modern Front-End Development for Rails: B7 no main folder in the source code (page xv)

On the page xv there is an instruction to run bin/setup from the main folder. I downloaded the source code today (12/03/21) and can’t see...

#errata /book-modern-front-end-development-for-rails

2 1452 11

2022-03-08 17:27:57 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

Programming Phoenix LiveView: B03 (page 56-57) auth exercise

Dear Sophie. I tried to do the “Authorization” exercise and have two questions: When trying to plug in an email-service, I found the ...

#question /book-programming-phoenix-liveview

1 1181 3

2021-05-04 15:14:02 UTC

New

PragProg Customers

iOS Unit Testing by Example: 54 Don't seem to be getting the print out on tests (Xcode 13.2)

Hey there, I’m enjoying this book and have learned a few things alredayd. However, in Chapter 4 I believe we are meant to see the “>...

#question /book-ios-unit-testing-by-example

0 1963 3

2022-01-24 15:18:41 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

Modern Front-End Development for Rails - application does not start after run bin/setup (page xviii)

After some hassle, I was able to finally run bin/setup, now I have started the rails server but I get this error message right when I vis...

#errata /book-modern-front-end-development-for-rails

0 1461 5

2022-06-03 09:50:10 UTC

New

PragProg Customers

Programming Machine Learning: some plot files are throwing error

I got this error when executing the plot files on macOS Ventura 13.0.1 with Python 3.10.8 and matplotlib 3.6.1: programming_ML/code/03_...

#question /book-programming-machine-learning

1 3055 5

2023-09-17 09:42:29 UTC

New

Other popular topics

General Dev>Dev Chat

What dev-related stuff have you been up to?

Reading something? Working on something? Planning something? Changing jobs even!? If you’re up for sharing, please let us know what you’...

#community

1052 22283 402

2026-03-23 08:22:18 UTC

New

General Dev>Dev Chat

Which language or framework do you want to learn next?

Curious to know which languages and frameworks you’re all thinking about learning next :upside_down_face: Perhaps if there’s enough peop...

#community #learning

243 6639 97

2025-12-01 07:17:12 UTC

New

Data Science

Genetic Algorithms in Elixir

From finance to artificial intelligence, genetic algorithms are a powerful tool with a wide array of applications. But you don't need an ...

#pragprog #ai /elixir #published-book /book-genetic-algorithms-in-elixir

25 5243 6

2021-02-09 12:32:09 UTC

New

General Dev>Hardware

Seen any cool new keyboards?

We have a thread about the keyboards we have, but what about nice keyboards we come across that we want? If you have seen any that look n...

/keyboards #mechanical-keyboards

49 5910 39

2025-05-10 22:54:44 UTC

New

General Dev>Hardware

Custom keyboard keycaps

There’s a whole world of custom keycaps out there that I didn’t know existed! Check out all of our Keycaps threads here: https://forum....

#hardware /keyboards #keycaps #mechanical-keyboards

15 11086 19

2023-07-27 16:30:57 UTC

New

Community>In The Spotlight

Spotlight: Peter Ullrich (Author) Interview and AMA!

Author Spotlight: Peter Ullrich @PJUllrich Data is at the core of every business, but it is useless if nobody can access and analyze ...

/elixir /phoenix /book-building-table-views-with-phoenix-liveview

72 4765 21

2023-10-17 17:07:59 UTC

New

Backend>Learning Resources

Ash Framework

Explore the power of Ash Framework by modeling and building the domain for a real-world web application. Rebecca Le @sevenseacat and ...

pragprog.com

#pragprog /elixir #published-book /ash /book-ash-framework

15 7555 9

2025-02-06 12:19:21 UTC

New

Game Dev>Chat

Hair Salon Games for Girls Fun

Hair Salon Games for Girls Fun Girls Hair Saloon game is mainly developed for kids. This game allows users to select virtual avatars to ...

#ios #android #unity #fun

2 3556 1

2025-02-27 10:48:33 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

AI>Chat

Claude Code's entire source just leaked (512K lines) - anyone else digging through it?

Woke up to this today: Claude Code’s complete source code exposed via npm source map. Not a snippet. All 512,000 lines. 1,900 TypeScript ...

#claude

1 5903 4

2026-04-02 21:40:32 UTC

New

Programming Machine Learning:

kai

Programming Machine Learning:

Most Liked

kai

Where Next?

Popular Pragmatic Bookshelf topics

Distributed Services With Go - gogoproto on linux