Sum in function object

I am trying to write a function object for the next function:

but I can't seem to use the + operator when working with function objs.

Tried writing it like this:

loss = @(W, x, y) log(sum(W'*x)) - (y(10)*W(:,10)'*x + y(9)*W(:,9)'*x + y(8)*W(:,8)'*x + ...
    y(7)*W(:,7)'*x + y(6)*W(:,6)'*x + y(5)*W(:,5)'*x+ y(4)*W(:,4)'*x + y(3)*W(:,3)'*x +y(2)*W(:,2)'*x + y(1)*W(:,1)'*x);
lossW = @(W) 0;
for i=1:n
    lossW = @(W) lossW + loss(W, X(:, i), Y(i, :));
end

I need to minimize with respect to the W matrix and I can't find a way to do that.

Answer 1

[Star Strider]

It is not possible to operate on funciton handles themselves. It is necessary to evaluate the functions —

loss = @(W, x, y) log(sum(W'*x)) - (y(10)*W(:,10)'*x + y(9)*W(:,9)'*x + y(8)*W(:,8)'*x + ...
    y(7)*W(:,7)'*x + y(6)*W(:,6)'*x + y(5)*W(:,5)'*x+ y(4)*W(:,4)'*x + y(3)*W(:,3)'*x +y(2)*W(:,2)'*x + y(1)*W(:,1)'*x);
for i=1:n
    lossW = @(W) lossW(W) + loss(W, X(:, i), Y(i, :));
end

In the loop, ‘lossW’ now has an argument.

The probllem is that ‘lossW’ now re-defines and refers to itself. This is called function recursion and is to be avoided. This code will lilkely not work without some significant changes.

[Stefan Nastase]

Thank you!