NABLA Nabla Ain't Basic Linear Algebra
Here are some words from Wikipedia:
A typical implementation looks like
The most amazing fact is that if all classes derive from our
base template class and share the same concept (read public interface) we can write generic functions like
which will take as its argument only objects of type that is aware of our concept, i.e. inherit
base. The situation when different types implement operations with the same names is called "static polymorphism".
This is one approach of implementation of the expression templates C++ programming technique which is used by this library.