Summation In Matlab With Vectors

I am trying to compute a summation over 1:N, and the expression is below:

I already defined the vectors = s11 and = smat and $Y_{dt}= Yd;

Any help would be appreciated! Thanks a lot

[Simon Dengler]

maby this helps: https://de.mathworks.com/help/matlab/ref/sum.html

[Irem Sara]

I am not sure if the latex code was showing, but the issue is I tried using the below code:

I get an error "Array indices must be positive integers or logical values." And I am not sure if the code is what is described in the summation.

for i=1:N
    chi(i,1)= sum(beta^(i+1)*gamma/s11(i,1) *(840*(1+eta)*exp(xi*Yd(i,1)-(1+eta)*smat(i,1))/(1+exp(xi*Yd(i,1)-(1+eta)*smat(i,1))))^(i-1));
end 

Answer 1

[David Hill]

No loop needed. Need to examine each array (s11,Yd,smat) and ensure they have the necessary elements (at least N). Recommend not using 'i' to index (something it can be confused for complex number).

I=(1:N)';
chi(I,1)= sum(beta.^(I+1)*gamma./s11(I,1).*(840*(1+eta)*exp(xi*Yd(I,1)-(1+eta)*smat(I,1))./...
    (1+exp(xi*Yd(I,1)-(1+eta)*smat(I,1)).^2)).^(I-1));%did not square the exp term in denominator

[Irem Sara]

I am not sure why but I still get the same error (even when I starts at 2, so that the lowest value is 1). I also made sure no element of the vectors is zero or undefined. Do you have any idea why this might be?

[David Hill]

Please attach all your variables and I will take a look.

[Irem Sara]

This actually worked in the end! Thank you very much- your response was super helpful