[Insight-users] Complexity of the metric?

[motes motes]

As I understand the metric is the most expensive part of the image
registration process. I assume that this follows from the fact that it
is linear in the number of voxels, meaning that if a volume has m*n*p
dimensions the number of computations of the metric is m*n*p. When
m=n=p is it then correct to say that the complexity of the metric is
O(n^3) ?