The function AccumulateVector adds the weighted vector Src to the vector Vec. The elements of the vector Src are multiplied by weight factor Wgt before they are added to Vec. This way it is possible not only to add but also to subtract the vector Src.
The function returns the following error codes:
0 ... everything is OK
1 ... Vec or Src has size zero
2 ... Vec and Src are not equal in size
