shawn_leong

shawn_leong

Machine Learning in Elixir: Plot of given `profits` function does not match the expected plot (B1.0, Chapter 3, Page 65)

Hey @seanmor5,

The function given in the book

defn profits(trees) do
  trees
  |> Nx.pow(4)
  |> Nx.negate()
  |> Nx.add(Nx.multiply(2, Nx.pow(trees, 3)))
  |> Nx.add(Nx.pow(trees, 2))
end

Results in the following plot which doesn’t match the expected plot in the book:

The accompanying Livebooks provides the following code to give the expected plot:

defn profits(trees) do
  -((trees - 1) ** 4) + trees ** 3 + trees ** 2
end

So my guess is that there is an error in the conversion to Nx functions.

Instead, the correct translation of the Livebook function should be as follows:

  defn profits(trees) do
    trees
    |> Nx.subtract(1)
    |> Nx.pow(4)
    |> Nx.negate()
    |> Nx.add(Nx.pow(trees, 3))
    |> Nx.add(Nx.pow(trees, 2))
  end
  • Adds the missing Nx.subtract(1) that the book doesn’t have
  • Removes the unnecessary doubling of the cube in Nx.add(Nx.multiply(2, Nx.pow(trees,3)))

This gives the correct expected plot

Marked As Solved

seanmor5

seanmor5

Author of Genetic Algorithms in Elixir

Thank you for pointing this out! I’ve fixed the issue in the next beta release!

Where Next?

Popular Pragmatic Bookshelf topics Top

New
johnp
Running the examples in chapter 5 c under pytest 5.4.1 causes an AttributeError: ‘module’ object has no attribute ‘config’. In particula...
New
brianokken
Many tasks_proj/tests directories exist in chapters 2, 3, 5 that have tests that use the custom markers smoke and get, which are not decl...
New
jdufour
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… ...
New
mikecargal
Title: Hands-on Rust: question about get_component (page 295) (feel free to respond. “You dug you’re own hole… good luck”) I have somet...
New
rmurray10127
Title: Intuitive Python: docker run… denied error (page 2) Attempted to run the docker command in both CLI and Powershell PS C:\Users\r...
New
leonW
I ran this command after installing the sample application: $ cards add do something --owner Brian And got a file not found error: Fil...
New
New
akraut
The markup used to display the uploaded image results in a Phoenix.LiveView.HTMLTokenizer.ParseError error. lib/pento_web/live/product_l...
New
taguniversalmachine
It seems the second code snippet is missing the code to set the current_user: current_user: Accounts.get_user_by_session_token(session["...
New

Other popular topics Top

AstonJ
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...
New
PragmaticBookshelf
Learn different ways of writing concurrent code in Elixir and increase your application's performance, without sacrificing scalability or...
New
AstonJ
We’ve talked about his book briefly here but it is quickly becoming obsolete - so he’s decided to create a series of 7 podcasts, the firs...
New
PragmaticBookshelf
Rails 7 completely redefines what it means to produce fantastic user experiences and provides a way to achieve all the benefits of single...
New
New
PragmaticBookshelf
Author Spotlight Mike Riley @mriley This month, we turn the spotlight on Mike Riley, author of Portable Python Projects. Mike’s book ...
New
AstonJ
If you want a quick and easy way to block any website on your Mac using Little Snitch simply… File > New Rule: And select Deny, O...
New
PragmaticBookshelf
Author Spotlight: Peter Ullrich @PJUllrich Data is at the core of every business, but it is useless if nobody can access and analyze ...
New
CommunityNews
A Brief Review of the Minisforum V3 AMD Tablet. Update: I have created an awesome-minisforum-v3 GitHub repository to list information fo...
New
AstonJ
If you’re getting errors like this: psql: error: connection to server on socket “/tmp/.s.PGSQL.5432” failed: No such file or directory ...
New

Sub Categories: