vector expression question.

[Tobias Burnus]

Tim Prince wrote:
> If you persuade a compiler to vectorize such a situation, you have no 
> control over the order of assignments.  I expect the compilers which 
> got the same result as for sequential execution did so by refusing to 
> vectorize.

I am not so sure. On one hand xser(:) = 2 and
   intel 10 x=1...
   Intel 11 x=2...
   Intel 12 x=2...
If I follow your suggestion, I would conclude that ifort 10 vectorizes 
the loop and ifort 11/12 don't, which is unlikely.

On the other hand, with gfortran I get the same result with -O0 and with 
-Ofast. And "-ftree-vectorizer-verbose=1" shows that gfortran vectorizes 
the loop with -Ofast.

Thus, it really depends on the internal algorithm. As the code is 
invalid, one cannot really tell which internal algorithm is better.

Tobias