How to calculate sum in 1.6?

[jeremysalwen]

http://sourceforge.net/p/viennacl/discussion/1143678/thread/38e942a0/
In this thread, is says that

FYI: Actually, we have recently agreed to include additional reduction operations such as sum() in the upcoming 1.6.0 release.

However, I cannot seem to find out how to interface with these functions. I can't seem to find a working sum() function in the documentation or code, and

Scalar<double>  linalg::reduce<op_add>(vector);

gives compile errors

ambiguous overload for ‘operator=’ 

[karlrupp]

Sorry for answering so late, I totally overlooked this :-/

reduce<> and friends are so far only prepared from the API point of view, but the implementations in the backends are still missing, i.e. they have (unfortunately) not made it into the 1.6.x release series. This is also the reason why you ran into the compilation issues.

As we've received a couple of requests regarding these reduction operations already, I scheduled this for the 1.7.0 release.