Tivadar Danka Profile picture
Apr 27, 2021 β€’ 6 tweets β€’ 2 min read β€’ Read on X
Have you ever wondered why include the logarithm in the definition of log-likelihood?

The answer is simple: logarithm makes differentiation of products easier.

Let's see why!

🧡 πŸ‘‡πŸ½
Although the derivative of a sum is the sum of derivatives, a similar property cannot be stated about the product of functions.

The derivative of a product is slightly more complicated: it is a sum of products.
The formula gets even more complicated when we have more functions in the product.

When potentially hundreds of terms are present, like in the likelihood function, computing this is not feasible.
This is where taking the logarithm can help us: it turns multiplication into addition!
So, instead of differentiating a product of 𝑛 functions, we have to deal with the sum!

Since the logarithm strictly increasing, it won't interfere with optimization either: the optimums are attained at the same place.
If you enjoyed this explanation, consider following me and hitting a like/retweet on the first tweet of the thread!

I regularly post simple explanations of seemingly complicated concepts in machine learning, make sure you don't miss out on the next one!

β€’ β€’ β€’

Missing some Tweet in this thread? You can try to force a refresh
γ€€

Keep Current with Tivadar Danka

Tivadar Danka Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @TivadarDanka

Jun 26
Problem-solving is at least 50% of every job in tech and science.

Mastering problem-solving will make your technical skill level shoot up like a hockey stick. Yet, we are rarely taught how to do so.

Here are my favorite techniques that'll loosen even the most complex knots: Image
0. Is the problem solved yet?

The simplest way to solve a problem is to look for the solution elsewhere. This is not cheating; this is pragmatism. (Except if it is a practice problem. Then, it is cheating.)
When your objective is to move fast, this should be the first thing you attempt.

This is the reason why Stack Overflow (and its likes) are the best friends of every programmer.
Read 18 tweets
Jun 25
What you see below is one of the most beautiful formulas in mathematics.

A single equation, establishing a relation between 𝑒, Ο€, the imaginary number, and 1. It is mind-blowing.

This is what's behind the sorcery: Image
First, let's go back to square one: differentiation.

The derivative of a function at a given point describes the slope of its tangent plane. Image
By definition, the derivative is the limit of difference quotients: slopes of line segments that get closer and closer to the tangent.

These quantities are called "difference quotients". Image
Read 20 tweets
Jun 24
"Probability is the logic of science."

There is a deep truth behind this conventional wisdom: probability is the mathematical extension of logic, augmenting our reasoning toolkit with the concept of uncertainty.

In-depth exploration of probabilistic thinking incoming. Image
Our journey ahead has three stops:

1. an introduction to mathematical logic,
2. a touch of elementary set theory,
3. and finally, understanding probabilistic thinking.

First things first: mathematical logic.
In logic, we work with propositions.

A proposition is a statement that is either true or false, like

β€’ "it's raining outside",
β€’ "the sidewalk is wet".

These are often abbreviated as variables, such as A = "it's raining outside".
Read 29 tweets
Jun 23
Understanding graph theory will seriously enhance your engineering skills; you must absolutely be familiar with them.

Here's a graph theory quickstart, in collaboration with @alepiad.

Read on: Image
What do the internet, your brain, the entire list of people you’ve ever met, and the city you live in have in common?

These are all radically different concepts, but they share a common trait.

They are all networks that establish relationships between objects. Image
As distinct as these things seem to be, they share common properties.

For example, the meaning of β€œdistance” is different for

β€’ Social networks
β€’ Physical networks
β€’ Information networks

But in all cases, there is a sense in which some objects are β€œclose” or β€œfar”. Image
Read 15 tweets
Jun 22
In machine learning, we take gradient descent for granted.

We rarely question why it works.

What's usually told is the mountain-climbing analogue: to find the valley, step towards the steepest descent.

But why does this work so well? Read on. Image
Our journey is leading through

β€’ differentiation, as the rate of change,
β€’ the basics of differential equations,
β€’ and equilibrium states.

Buckle up! Deep dive into the beautiful world of dynamical systems incoming. (Full post link at the end.)
First, let's talk about derivatives and their mechanical interpretation!

Suppose that the position of an object at time t is given by the function x(t), and for simplicity, assume that it is moving along a straight line β€” as the distance-time plot illustrates below. Image
Read 27 tweets
Jun 21
Matrix factorizations are the pinnacle results of linear algebra.

From theory to applications, they are behind many theorems, algorithms, and methods. However, it is easy to get lost in the vast jungle of decompositions.

This is how to make sense of them. Image
We are going to study three matrix factorizations:

1. the LU decomposition,
2. the QR decomposition,
3. and the Singular Value Decomposition (SVD).

First, we'll take a look at LU.
1. The LU decomposition.

Let's start at the very beginning: linear equation systems.

Linear equations are surprisingly effective in modeling real-life phenomena: economic processes, biochemical systems, etc. Image
Read 19 tweets

Did Thread Reader help you today?

Support us! We are indie developers!


This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Don't want to be a Premium member but still want to support us?

Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Or Donate anonymously using crypto!

Ethereum

0xfe58350B80634f60Fa6Dc149a72b4DFbc17D341E copy

Bitcoin

3ATGMxNzCUFzxpMCHL5sWSt4DVtS8UqXpi copy

Thank you for your support!

Follow Us!

:(