MATLAB: My script won’t run (error) how to fix it

Question

My script is below. When it runs (using [left, right] = search(a, 367, 1, 100)) it shows this message: Index exceeds matrix dimensions.

Error in search (line 12) if vec(midPt) == targetVal

It should output the index 73 – how can I fix it?

My Script:

function [left, right] = search(vec,targetVal,left,right)
  % SEARCH Binary search algorithm step.
  %  [left, right] = SEARCH(vec,targetVal,left,right) returns the end points
  %   produced by one step of the binary search algorithm with
  %   target value targetVal. The elements of vec must be in ascending order.
    % Compute the mid-point by halving the distance between
    % the end points and rounding to the nearest integer.
    while left < right
        midPt = round((left + right)/2)
        if vec(midPt) == targetVal
      % targetVal has been found
        left = midPt;
        right = midPt;
        elseif vec(midPt) < targetVal
        % targetVal must be before midPt
        right = midPt - 1;
        else
        % targetVal must be after midPt
        left =  midPt + 1;
        end
    end

Answer 1

For [left, right] = search(a, 367, 1, 100) ;

left = 1; right = 100 ; midPt = round((left + right)/2) ; midpt = 51

Your size of a would be less then 51, so the error popped out. Check your size of a