creating algorithm for specific computation

I need to perform below computation using algorithm approach.

t=100; % constant et=1:1:4; % the numbers of "et" are variable.

result=(((t-et(2))*(t-et(3))*(t-et(4)))/((et(1)-et(2))*(et(1)-et(3))*(et(1)-et(4))))+(((t-et(1))*(t-et(3))*(t-et(4)))/((et(2)-et(1))*(et(2)-et(3))*(et(2)-et(4))));

How can I create algorithm to perform above computation automatically with respect to the array number of et?

Answer 1

[Guillaume]

If I understood correctly:

numerators = t - repmat(et(:), 1, numel(et));  %calculate t-et(1), t-et(2), etc.
numerators(logical(eye(size(numerators)))) = 1; %replace t-et by 1 on diagonal
numerators = prod(numerators); 

denominators = et - et';
denominators(logical(eye(size(denominators)))) = 1;
denominators = prod(denominators);

result = sum(numerators ./ denominators);

However, the result of this is always going to be 1. So

result = 1;

may be simpler.

[sermet]

I got "Matrix dimensions must agree" error for denominators = et - et'; line

[Guillaume]

That would be because you're using an ancient version of matlab (< R2016b). In older versions:

denominators = bsxfun(@minus, et, et');