Question

guys im stuck in lecture 8 how can i uderstand O big Notation.i know nothing about pure mathematics

Answer 1

The big O notation is simply an expression of what the problem size of a function is bounded by with respect to its input.

Answer 2

It's a way to denote the computational complexity of a function.

Answer 3

Most of the stuff where he's deriving out how many operations the program is performing each step aren't really important to understand. They're just there to give a bit of a background.

You'll do fine if you just have a general sense of which functions are more efficient.

Answer 4

If you're familiar with limits in calculus you could think of it as the limit of the size of the problem (steps involved to get a solution from an algorithm) as the size of the input tends to infinity.

And yeah the derivation stuff isn't that important it's just to illustrate it more literally.

Answer 5

see u just brought in another term wats a derivate.i tried to search out cant find anything.or maybe any reference i can find in plain english

Answer 6

When someone shows you something like:

O(1)
O(n)
O(n^2)
O(c^n)
or even O(log(n))

they may all mean different things but they all basically describe how much more time it takes for the computer to get an answer to a problem.

for a function with O(n), or as the handsome guy in the lecture would say 'linear computational complexity', it just means that the problem's difficulty grows according to the size of n.

Answer 7

if I put an input of size 2 for a function with linear computational complexity, or O(n) to show big oh notation (or is it big O notation whatever), the function takes twice as long to complete.

if I put an input of size 4, the function with O(n) takes 4 times as long. an input with size n takes n times as long for the function to work out a solution.

Answer 8

sounds simple to digest.

Answer 9

he explains the meaning of the other Os throughout the lecture and gives examples of them.

Answer 10

it is not necessary to know exactly what a derivative is. But if you want to learn, and believe me it took watching a fair few videos, but use Khan academy and the mathematics section of this website.

It is in the stream of calculus. It kinda means were you have a graph which is not a straight line, you use a derivative to find the slope at any given point on the graph.