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Summation questionby joshmccraney
Tags: summation 
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#1
Jan2014, 06:37 PM

P: 322

hey pf!
can someone explain to me what to do if presented with an equation like this: [tex]\sum_{i=1}^{n}A_i=i[/tex] is this identical to stating [itex]A_i=i[/itex]? either way, can you please explain. thanks! josh 


#2
Jan2014, 06:44 PM

Mentor
P: 21,215

Where did you see this? If it's from a textbook, can you post a picture? 


#3
Jan2014, 08:23 PM

Engineering
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Thanks
P: 6,951

Just taking it at face value, it means
##A_1 + A_2 + \cdots + A_n = i## The ##i## in the sum is a "bound variable" or "dummy variable". You could replace it by anything else (except ##n##) without changing the meaning. The ##i## on the right hand side means ##i##. But using ##i## twice in one equation like that is horrible, as Mark44 said. It would have been more literate to write something like $$\sum_{k=1}^n A_k = i$$ 


#4
Jan2014, 08:29 PM

P: 322

Summation question
yea, i was trying to generalize for determining the fourier coefficients. i have a link here on pf: http://www.physicsforums.com/showthread.php?t=733877
my question there has been answered, but if you're curious to this type of problem, there's the link. 


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