Question

Why is professor referring to V as a vector in this video?

http://www.youtube.com/watch?v=BRjwkgQct28&feature=player_detailpage#t=2450s

Could not something scalar, such as a binary list, serve just as well as a set of vectors?

Answer 1

when you have more items to save you need a vector :-)

Answer 2

Vectors are used a lot more commonly than lists. I'm not sure exactly what the context is, but lists are only particularly helpful when you are inserting or removing lots of things, and not at the end of the collection.

Answer 3

We are looking at \[\sum_{i=1}^{n}V[i]I[i]\] where I is a set of vectors we are analyzing and V is a set of 1/0 of the same length. So if V[i]=1, we add I[i] to the sum, and if V[i]=0, we skip I[i]. So I don't understand what the convenience of using vector V vs scalar V in this scenario.

Answer 4

@sakh
ok, let's say we use a scalar for this job; how could we save n different values in a scalar V that can save 1 value only ? You could think settings 1 bit of the scalar V for each item of the vector I, but then how many bits should be the scalar composed of ?

Answer 5

@nick67
n bits

Answer 6

Exactly ! Now, what can we do if we need to manage a vector I with, let's say, 1000 items ? Should we use a scalar 1000 bits long? It doesn't exist.

Answer 7

@nick67
Oh ok, and we can store a vector representation in of this in something as simple as a sinx?

Answer 8

What do you mean ? Do you need to create a vector storing values of the function sinx ?

Answer 9

I mean that any vector can be represented as\[A \sin B\]
right?

Answer 10

Uhm, sorry but I can't understand well; a vector is only a memory location where you can save many values. How would you like to use it ?

Answer 11

Right. I was thinking of a geometric meaning, Did not know it meant a different thing in Python. Thanks, I get it now.

Answer 12

you're welcome