algorithm algorithm CBS The circular binary segmentation (CBS) algorithm divides the genome into regions of equal copy number . The algorithm tests for change-points using a maximal t-statistic with a permutation reference distribution to obtain the corresponding p-value. The number of computations required for the maximal test statistic is O(N^2),where N is the number of markers. This makes the full permutation approach computationally prohibitive for the newer arrays that contain tens of thousands markers and highlights the need for a faster algorithm.