Explain yourselves, comp sci.

It's a dynamically-sized list of objects of the same type stored contiguously in memory.
- It's like a fancy list.
  
  It's a dynamically-sized list of objects of the same type stored contiguously in memory.
  dynamically-sized: The size of it can change as needed.
  list: It stores multiple things together.
  object: A bit of programmer defined data.
  of the same type: all the objects in the list are defined the same way
  stored contigiously in memory: if you think of memory as a bookshelf then all the objects on the list would be stored right next to each other on the bookshelf rather than spread across the bookshelf.
  
  Many things like each other lined up in a row, and you can take some away or put more in.
  
  It's how you want an array to work.
- No, it's an n-tuple with certain algebraic properties.
  
  This is such an understated but useful description in this context. It's also how I understood algebra for applied matrix computation.
  
  Its the algebraic properties that are important, not all vectors are n-tuples, eg the set of polynomials of degree less than n.
  You need a basis to coordinate a vector, you can work with vectors without doing that and just deal with the algebraic properties. The coordinate representation is dependent on the basis chosen and isn't fundamental to the vector. So calling them n-tuples isn't technically correct.
  You can turn them into a set of coordinates if you have a basis, but the fact that you can do that is because of the algebraic properties so it's those properties which define what a vector is.
- So an ArrayList?
  
  No. ArrayList is thread safe and implements the collections API. Vector doesn't. Though if you're using Java, there's almost no instance where you would want to use a Vector instead of ArrayList.

Did nobody else's CS department require a bunch of linear algebra courses? A vector is an element of vector space.
- Sets are just objects in the category of Set.
- That is quite possibly the least helpful answer you could give.
  
  Also the most correct :)
  
  Q: what is a vector? A: it is a vector
- We do and we know this. Maybe programmers would give that answer
- My university requires two for the CS program, as I recall.

What do you mean? A vector is a direction and magnitude!
- Maybe they mean std::vector in C++?
  
  It's a terrible name. The math answer is what I would give.
- The only correct answer for a 101 introduction. It’s an incredible powerful intuition even in contexts where vectors are seemingly used as a list of numbers.
- You can also define a vector by the equivalent “sides of the right triangle”. In 2D, the x,y coordinates. In computer science, vectors are n-tuples, so they represent a math/physics vector but in n-dimensions.
- Yes, and as linear algebra teaches, to convert a vector from direction and magnitude to a list of numbers (components), follow these steps:
  Let the magnitude of the vector be represented by the symbol |A| or A.
  Let the direction of the vector be represented by the angle θ, which is measured counterclockwise from the positive x-axis.
  The x-component of the vector is given by: Ax = |A| cos(θ)
  The y-component of the vector is given by: Ay = |A| sin(θ)
  The vector can now be represented as a list of numbers: A = (Ax, Ay)
  For example, if a vector has a magnitude of 5 units and a direction of 30° counterclockwise from the positive x-axis, its components would be:
  Ax = 5 cos(30°) ≈ 4.33 units Ay = 5 sin(30°) ≈ 2.50 units
  The vector can now be written as A = (4.33, 2.50)
  source

Ooh, do tensors next!
You should ask your biologist friend and your physicist friend and your compsci friend to debate about what vectors are. Singularities, too.
- Singularities, too.
  /dev/null
- Tensors are easy!
  
  It’s just a fancy list of fancy lists! :D

you just need to car and cdr your cons cell …

Well mathematically isn't it an n by 1 matrix.
- Not always. Any m by n matrix is also a vector. Polynomials are vectors. As are continuous functions.
  A vector is an element of a vector space over a field. These are sets which have a few operations, vector addition and scalar multiplication, and obey some well known rules, such as the existence of a zero vector (identity for vector addition), associativity and commutativity of vector addition, distributivity of scalar multiplication over vector sums, that sort of thing!
  These basic properties give rise to more elaborate concepts such as linear independence, spanning sets, and the idea of a basis, though not all vector spaces have a finite basis.
  
  How are polynomials vectors how does that work?
  Say u have polynomial f(x)= a + bx + cx^{2 + dx}3
  How is that represented as a vector? Or is it just one of those maths well technically things? Cos as far as I'm aware √g = π = e = 3.
  Are differential eqs also vectors?
  
  Wouldn't N by M be a tensor? Magnitude and direction only need one entry per DOF.

It's an array.
First time I heard of vectors in comp-sci was in C++. The naming still doesn't make sense to me.
Anti Commercial-AI license
- NO
  
  YES

I asked my math friend. He said a vector is magnitude plus velocity.
- It should be magnitude plus orientation, not velocity. Velocity itself is a vector quantity

As a mathematician this genuinely hurts. Lol.

A vector is a list of numbers, at its most basic. You can add a lot of extra functionality to it, but at its core, its just a list.
- Functions from the reals to the reals are an example of a vector space with elements which can not be represented as a list of numbers.
  
  It still can be, just not on infinite precision as nothing can with fp.

This might hit harder if it weren't for the fact that words very can have multiple senses