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

GilWright
Working through the steps (checking that the Info,plist matches exactly), run the demo game and what appears is grey but does not fill th...
New
jesse050717
Title: Web Development with Clojure, Third Edition, pg 116 Hi - I just started chapter 5 and I am stuck on page 116 while trying to star...
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
AleksandrKudashkin
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...
New
gilesdotcodes
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...
New
Chrichton
Dear Sophie. I tried to do the “Authorization” exercise and have two questions: When trying to plug in an email-service, I found the ...
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
brunogirin
When running tox for the first time, I got the following error: ERROR: InterpreterNotFound: python3.10 I realised that I was running ...
New
tkhobbes
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...
New
andreheijstek
After running /bin/setup, the first error was: The foreman' command exists in these Ruby versions: That was easy to fix: gem install fore...
New

Other popular topics Top

AstonJ
Or looking forward to? :nerd_face:
498 13326 269
New
dasdom
No chair. I have a standing desk. This post was split into a dedicated thread from our thread about chairs :slight_smile:
New
PragmaticBookshelf
From finance to artificial intelligence, genetic algorithms are a powerful tool with a wide array of applications. But you don't need an ...
New
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
New
AstonJ
Do the test and post your score :nerd_face: :keyboard: If possible, please add info such as the keyboard you’re using, the layout (Qw...
New
Exadra37
I am asking for any distro that only has the bare-bones to be able to get a shell in the server and then just install the packages as we ...
New
PragmaticBookshelf
Build efficient applications that exploit the unique benefits of a pure functional language, learning from an engineer who uses Haskell t...
New
Help
I am trying to crate a game for the Nintendo switch, I wanted to use Java as I am comfortable with that programming language. Can you use...
New
New

Sub Categories: