mwomick

mwomick

The Ray Tracer Challenge: p. 28

The Ray Tracer Challenge by @jamis: p. 28

It appears to me that on page 28, there is an error. The first column of the features/matrices.feature A*B matrix is:

20

44

40

16

whereas my program computed

8

8

-8

-8

Is this an error or have I gotten something wrong?

https://www.symbolab.com/solver/matrix-multiply-calculator/%5Cbegin%7Bpmatrix%7D1%262%263%264%5C%5C%205%266%267%268%5C%5C%209%268%267%266%5C%5C%205%264%263%262%5Cend%7Bpmatrix%7D%5Ccdot%5Cbegin%7Bpmatrix%7D-2%261%262%263%5C%5C%20-3%262%261%26-1%5C%5C%204%263%266%265%5C%5C%201%262%267%268%5Cend%7Bpmatrix%7D

Marked As Solved

jamis

jamis

Author of Mazes for Programmers and 1 other title

It looks like you might have a typo in your second matrix (“B”). In the second row, the first number is a positive “3”, rather than negative. That should get you the expected answer.

  • Jamis

Where Next?

Popular Pragmatic Bookshelf topics Top

telemachus
Python Testing With Pytest - Chapter 2, warnings for “unregistered custom marks” While running the smoke tests in Chapter 2, I get these...
New
lirux
Hi Jamis, I think there’s an issue with a test on chapter 6. I own the ebook, version P1.0 Feb. 2019. This test doesn’t pass for me: ...
New
HarryDeveloper
Hi @venkats, It has been mentioned in the description of ‘Supervisory Job’ title that 2 things as mentioned below result in the same eff...
New
New
Charles
In general, the book isn’t yet updated for Phoenix version 1.6. On page 18 of the book, the authors indicate that an auto generated of ro...
New
dsmith42
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 “>...
New
rainforest
Hi, I’ve got a question about the implementation of PubSub when using a Phoenix.Socket.Transport behaviour rather than channels. Before ...
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
redconfetti
Docker-Machine became part of the Docker Toolbox, which was deprecated in 2020, long after Docker Desktop supported Docker Engine nativel...
New
SlowburnAZ
Getting an error when installing the dependencies at the start of this chapter: could not compile dependency :exla, "mix compile" failed...
New

Other popular topics Top

malloryerik
Any thoughts on Svelte? Svelte is a radical new approach to building user interfaces. Whereas traditional frameworks like React and Vue...
New
AstonJ
I ended up cancelling my Moonlander order as I think it’s just going to be a bit too bulky for me. I think the Planck and the Preonic (o...
New
dimitarvp
Small essay with thoughts on macOS vs. Linux: I know @Exadra37 is just waiting around the corner to scream at me “I TOLD YOU SO!!!” but I...
New
PragmaticBookshelf
Learn different ways of writing concurrent code in Elixir and increase your application's performance, without sacrificing scalability or...
New
PragmaticBookshelf
Create efficient, elegant software tests in pytest, Python's most powerful testing framework. Brian Okken @brianokken Edited by Kat...
New
PragmaticBookshelf
Author Spotlight Rebecca Skinner @RebeccaSkinner Welcome to our latest author spotlight, where we sit down with Rebecca Skinner, auth...
New
New
PragmaticBookshelf
Programming Ruby is the most complete book on Ruby, covering both the language itself and the standard library as well as commonly used t...
New
hilfordjames
There appears to have been an update that has changed the terminology for what has previously been known as the Taskbar Overflow - this h...
New
AstonJ
Curious what kind of results others are getting, I think actually prefer the 7B model to the 32B model, not only is it faster but the qua...
New

Sub Categories: