Activating and deactivating the API-active state is achieved through calls to place HR here
place HR here The above calls should be regarded as barriers: all nodes in the PLAPACK base communicator must make the call.
The API state of PLAPACK can be queried with the call place HR here
place HR here This will return
PLA_STATE_NORMAL or
PLA_STATE_API_ACTIVE.
While PLAPACK is in the API-active state, the calls described in
this chapter can be used to access the contents of linear
algebra objects.
We shall see in the next chapter that communication in
PLAPACK is achieved through calls to the copy and
reduce operations. Since these operations in turn
call MPI, they may not be called while PLAPACK is API-active.
In subsequent sections, global operations are given
that themselves call the copy and reduce operations.
These cannot be called while in API-active state either.
In Appendix 
, we indicated
whether a call is
API-safe, meaning that the call can be made while
PLAPACK is API-active.
Failure to observe these restrictions can result in
the contents of an object becoming inconsistent
and/or an application deadlocking.