How to form an array of sums?

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Yuval
Yuval on 19 Oct 2013
Commented: Anthony on 20 Oct 2013
Hi, I am asked to evaluate the following sum S=Sigma(n=0 to N) x^n/n! (namely, e^x as n->Inf) for N=10:10:100 and x=10, so that every element S(i) is a partial sum which approximates function e^x with different accuracy. Below is my code, which doesn't work:
x=10; N=10:10:100; S=symsum(x^n/sym('n!'), n, 0, N)
Would anyone please tell me where I am going wrong and how it may be corrected? I'd appreciate some guidance.

Answers (1)

Anthony
Anthony on 19 Oct 2013
Edited: Anthony on 19 Oct 2013
syms n;
x=10;
N=100;
% N cannot be a vector (if you want N=10:10:100, use a loop instead.)
S=double(symsum(x^n/sym('n!'), n, 0, N))
  2 Comments
Yuval
Yuval on 19 Oct 2013
Hi Anthony, Thank you very much for your reply. I am now trying the following, albeit, alas, it still does not quite work:
x=10; N=10; i=0; while (N<=100), S(i)=double(symsum(x^n/sym('n!'), n, 0, N)); i=i+1; N=N+10; end
Could you please advise?
Anthony
Anthony on 20 Oct 2013
Edited: Anthony on 20 Oct 2013
add 'syms n;', and initialize i=1 instead of 0.

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