Help writting a simple code!

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Hossein sadri
Hossein sadri 2011-6-29
I'm trying to make a Simulink model consisting of a clock (as a source) and a MATLAB function that calculates the following:
Y=exp(t) * sigma(n=1:inf)[n * exp(n*t)]
Can anybody help me write the code?

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回答（5 个）

Paulo Silva
Paulo Silva 2011-6-29
MATLAB Fcn
exp(u)*sum([1:10].* exp([1:10].*u)) %not infinite sum but close enough
C.J. Harris
C.J. Harris 2011-6-29
You won't be able to write an infinite series directly. You will either have to use an approximation, or only calculate the sum for the first 'n' elements.
Walter Roberson
Walter Roberson 2011-6-29
If and only if t is less than 0,
Y = exp(2*t)/(exp(t)-1)^2
That is, sum(n*exp(n*t), n = 1 .. infinity) is exp(t)/(exp(t)-1)^2
If t is 0 or greater, the sum is infinite, as you are adding together numbers that increase infinitely.
Hossein sadri
Hossein sadri 2011-6-30
tnx for the answers....and what should i do when i want to do same thing with sigma(n^2*exp(u))?im encountering the error matrix must be squer using [1:10]^2....
  2 个评论
Walter Roberson
Walter Roberson 2011-6-30
n.^2 instead of n^2
But n^2*exp(u) has the same problem I described above of having an infinite value unless u is negative.

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amey
amey 2011-7-1
n=1:1:100; y=exp(0.4)*(n.*exp(0.4*n)); tot=0; for i=1:100; tot=tot+y(i); end disp(tot);
  2 个评论
amey
amey 2011-7-1
u = 0.4 ; % assumed
n=1:1:100; % only first 100 terms taken
Paulo Silva
Paulo Silva 2011-7-1
is there another question for us?

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