Methods add, sub missing in FP12, FP24, FP48

[webmaster128]

Is there a reason those methods don't exist? I don't strictly need them but am curious for consistency reasons.

[mcarrickscott]

These methods could easily be added. However as you observe, there is no current requirement for them. The group G_T is multiplicative, and hence addition is not a requirement. Elliptic curves over these fields is never required, as we would always be using a twisted curve of lower extension.