Help me interpret this funny Maths thing

[squance]

This is for an engineering assignment...and I don't understand it at all...

Its related to huffman coding



where n is the number of symbols
w_i is the probability of the symbol i
and lenghth(c_i) is the number of bits in teh codeword for symbol i


say i got n = 7
w_i=0.222
length (ci) is 2


Can someone please explain to me how to put the figures in that formula above...its so hard to understand...

[excal]

I'll have a look at this tomorrow

[squance]

I'll have a look at this tomorrow

Lol i just wanted to know how to interpret this..and how to plug in numbers...

[Mao]

(Image removed from quote.)

where n is the number of symbols
w_i is the probability of the symbol i
and lenghth(c_i) is the number of bits in teh codeword for symbol i


say i got n = 7
w_i=0.222
length (ci) is 2

there's not enough information given. In this case, you have 7 symbols, hence you would have a probability relating to each, and a length related to each symbol

the "i" is just an index so you can differentiate between symbol 1 and symbol 2. the i by itself in fact doesn't have any meaning [other than to mean "a particular thing"]

the formula basically mean, for each "i" multiply the length by the probability. Add this up for all "i"s to get L(C)

expanding this formula:

[excal]

(Image removed from quote.)

where n is the number of symbols
w_i is the probability of the symbol i
and lenghth(c_i) is the number of bits in teh codeword for symbol i


say i got n = 7
w_i=0.222
length (ci) is 2

there's not enough information given. In this case, you have 7 symbols, hence you would have a probability relating to each, and a length related to each symbol

the "i" is just an index so you can differentiate between symbol 1 and symbol 2. the i by itself in fact doesn't have any meaning [other than to mean "a particular thing"]

the formula basically mean, for each "i" multiply the length by the probability. Add this up for all "i"s to get L(C)

expanding this formula:

Yeah, that's exactly it.

Basically, it finds the expected bit length of codewords in the symbols.

You'll need distinct values for each element of 'w' and 'c', as they are an array of values (of length 7, as n = 7).

Basically (assuming your given values of and ):













...

[Collin Li]

http://en.wikipedia.org/wiki/Summation_notation

[squance]

Thank you so much guys!!!!
I now understand! (but why do they have to represent it in a funny way with that funny e sign? it makes dummies like me feel even more dummier...)

[/0]

'Sigma' is the Greek S and stands for 'Sum'. That's why it's most appropriate to use that symbol. The numbers above and below are simply the lower and upper bounds of summation, analogous to what you would see in integration. It makes writing large (and even infinite) sums significantly simpler.

[Mao]

mathematicians are lazy

is a shorthand way of representing

similarly, you may encounter this

[squance]

mathematicians are lazy

is a shorthand way of representing

similarly, you may encounter this

Eww!! I don't like symbols like that...they just confuse me even more!

[Mao]

(incidentally, this is also "10!")

maybe these symbols are a bit more friendly

[excal]

You thought that one was nasty? Try this one:



Fun statistics. You'll find stats (i.e., 'Quantitative Methods') littered with these kinds of summation equations.

[Ahmad]

Concrete Mathematics has a superb treatment of sums (among other things) for those interested.

[xox.happy1.xox]

  Maths is hard