Mid point value of a function

I need to find the sum with value of T at mid of every subinteval

 for j= 1:1:n+1
   Rsum2=Rsum2+bb(j+1)*T(j+1/2)
  end

but get an error

"Array indices must be positive integers or logical values."

How can I find value of T at midpoint of every interval in this loop?

[David Hill]

Your question is confusing, what is bb and T? Provide a simple example of what you want for your output.

[Mubashara Wali]

Leave bb. Its just a coefficient. T is a function. Suppose my interval is [0,1] with n subintervals and I need to find the sum of the function at midpoint of every subinterval.

[Mubashara Wali]

How can I find this sum in a loop?

Answer 1

[Jan]

T(j+1/2) is not valid, when T is a vector. You need integer values as indices.

Perhaps you mean:

(T(j) + T(j+1)) / 2

Answer 2

[Jan]

interval is [0,1] with n subintervals and I need to find the sum of the function at midpoint of every subinterval.

n        = 27;
interval = linspace(0, 1, n);

% If T is vectorized:
Result = sum(T(interval(1:n-1) + interval(2:n)) / 2)

% If T works for scalars only:
Result = 0;
for k = 1:n-1
    Result = Result + T(0.5* (interval(k) + interval(k+1)));
end