Author Topic: some weird probability notation (Read 1150 times) Tweet Share

ElephantStew · « **on:** August 18, 2008, 05:45:37 pm »

okay guys i need to know what this means:
[IMG]http://img168.imageshack.us/img168/188/equationdm0.th.jpg[/img]
i didnt know how to get the equation using latex
thanks in advance

Collin Li · « **Reply #1 on:** August 18, 2008, 05:59:55 pm »

$\displaystyle\sum_{x=0}^3 Pr(X=x) = 1$

It means this:

$Pr(X=0) + Pr(X=1) + Pr(X=2) + Pr(X=3) = 1$

See Summation notation

$\displaystyle\sum_{x=0}^3 Pr(X=x)$ means to add up $Pr(X=x)$ starting from $x=0$ , moving up by increments of 1 (implied by the summation notation), until we get to $x=3$ .

It's sort of like a "discrete" integral, in that the lower number is your starting point, and your upper number is your ending point (interval in integration).

excal · « **Reply #2 on:** August 18, 2008, 06:08:24 pm »

Quote from: ElephantStew on August 18, 2008, 05:45:37 pm

okay guys i need to know what this means:
[IMG]http://img168.imageshack.us/img168/188/equationdm0.th.jpg[/img]
i didnt know how to get the equation using latex
thanks in advance

Using coblin's example:

$\sum_{x=0}^3 Pr(X=x) = 1$

Code: [Select]

\sum_{x=0}^3 Pr(X=x) = 1

ElephantStew · « **Reply #3 on:** August 18, 2008, 06:10:39 pm »

ahhh okay, thanks coblin and Excalibur

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Author Topic: some weird probability notation (Read 1150 times) Tweet Share

ElephantStew

some weird probability notation

Collin Li

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excal

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ElephantStew

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