Neural Networks for beginners: intro to back propagation!

continuing our learning of how to build neural networks from scratch, in this video we learn how to minimize the cost function (aka how accurate our predictions are to actual values). we do this with a technique called "back propagation"!
well start with a simple example using just 1 training data point. in the next video we'll learn how to generalize to a larger dataset!

[@vwhxss-390]

many thanks this is really helpful.

[@JenFoxBot]

Yayyy so glad to hear!!

[@BrianOSheaPlus]

Very good explanation, thanks. One question: at about 9:59 you mention the derivative of something that sounded like the "zemon function". I'm sure I'm mishearing it though. What is the zemon function? In this context, it sounds like it's the activation function. Is that correct?

[@JenFoxBot]

Yes, the zieman function! It's the format for the hypothesis function that is used for a neural network. Check out the earlier neural network videos to learn more about the zieman function!

[@BrianOSheaPlus]

@@JenFoxBot thanks!

[@mmason4242]

So cost function is predictive, while the back propagation validates the predictive accuracy of the cost function, right?

[@JenFoxBot]

The cost function is the *error* between the hypothesis function ( the predictive equation modeled by the zieman function aka 1/(1-e^z)). And backpropagation helps us minimize the cost function, aka find the smallest error between hypothesis function and the actual training data. Hope that helps !

[@mmason4242]

Yes and thanks much

[@BradleyG01]

Thumbnail is clickbait. Shows someone being happy in the context of neural networks.

[@JenFoxBot]

😂 lol well I love math and I don't have to take tests anymore so... Yes! I was actually stoked to do this! And also, I feel ya, it can be exhausting and stressful when you're in school! Hang in there, you got this 💖

[@kingbroseph9773]

​@@JenFoxBot Can't wait to learn maths outside of academic settings 🥲🥲🥲

[@gmlgml780]

Yeah. Lovely ? Humans ? You seemed a pretty clever one. I dunno, maybe math took your clear sight, but I saw only one lovely one. Ever. (And she was pretty mean 2 me.)

[@DB-nl9xw]

upload in 4K also share a link with the slides of the video

[@JenFoxBot]

There are no slides and I make these for free so it's not super helpful or appreciated to ask me to do things like this.

[@DB-nl9xw]

@@JenFoxBot delete the comment then -- it's very hard to read what you are writing

[@JenFoxBot]

@@DB-nl9xw that is actionable feedback re hard to see what I'm writing. I prefer to have dialogue when possible vs deleting comments bc it's an educational process for us both.

[@abdelnacer7721]

I'm focusing on your smile more then the lesson 😂

[@TechnoViking__]

1st