There's a summation equation that I need to implement for various values of a variable x. Please help.

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Mayank Kashyap
Mayank Kashyap 2017-2-7
评论： Walter Roberson 2017-2-7
The equation in question is:
P_bl= (A^Kcell/ Kcell ! ) * ( Summation (k=0 to Kcell) of A^k/ k !)^ -1
I have to prepare a MATLAB code for obtaining values of P_bl for varying values of A and Kcell. i. A=70 and Kcell=70:100 ii. Kcell= 75 and A= 40:160
Please help.
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Mayank Kashyap
Mayank Kashyap 2017-2-7
编辑：Mayank Kashyap 2017-2-7
Well, my bad I guess. New to MATLAB and this community. Please bear with me and help me out.
I've attached the file here and will paste the code after this too:
x=70:100;
%x is Kcell here
A=70;
syms k x
S=(symsum(A.^k/factorial(k),k,0,x))^-1;
for i=1:length(x)
P_bl(i)= ((A^x)/factorial(x))*S;
end
plot(P_bl,x)

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回答（1 个）

Walter Roberson
Walter Roberson 2017-2-7
http://www.mathworks.com/matlabcentral/answers/322453-n-term-approximation-for-matrices#answer_252568
You have the significant problem that A^k is not defined for vector A. A^k is defined for scalars and for square matrices.
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Walter Roberson
Walter Roberson 2017-2-7
length(x) is 1 because of "syms x" .
syms x
means the same thing as
x = sym('x')
that is, x is overwritten with the symbolic name x. This destroys any previous meaning it had.
Perhaps in your symsum you mean that you wanted to process it for all the various values that are in the x vector you used. If so, then
syms k N
S=(symsum(A.^k/factorial(k),k,0,N))^-1;
subs(S, N, x)
Now look at
P_bl(i)= ((A^x)/factorial(x))*S
This does not involve "i" at all. Also, the symsum version is building a total but the loop version is not building a total.

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