算法从中间向外循环一个数组？

I'm working on a divide-and-conquer algorithm (in fact, one that does curve fitting to a number of input points). For the 'divide' part, I need to calculate an error term for each point, and if the error exceeds a given threshold, I wish to split the curve at that point and process the left and right sections of the input separately. A simple loop does the trick; but it would be advantageous for me to start at the middle of the current section and work outwards. (To clarify: if I do find a point whose error is too large, I recursively call and generate separate curves for the left and right sections - if all the points are within the threshold, then my curve fits and I return).I'm working on a divide-and-conquer algorithm (