Problem: Steering is intended to calculate values for corrector magnets whose
effect will be to reduce the RMS of the beam orbit as read by BPMs. The
problem is steering only reads the existing settings (BDES) of the correctors o`
when it's initialized. From that point on, it thinks that the extant settings
(BDESes) of the correctors are the values which it last calculated. That
means if steering takes a long time to calculate new settings, the real
extant BDESes of the correctors in the db may have changed due to external
influences, such as someone implementing a "bump", before steering has the
chance to implement the values implied by the calculation it made. If the
bump is "closed" (if its effect is local in the beamline), then it should be
ok for steering to implement its correction even though the bump is in effect.
However, since steering has only recorded the extant corrector BDESes before it
started its calculation, and the bump changed those values, and steering then
implements its calculated change to the corrector settings assuming that
change is the change to the recorded BDESes, the effet is to undo the BUMP.
Furthermore, over a long steering session like the GOF, steering never
reacquires the real corrector settings. So any number of external influences
will be causing steering to implement changes to magnets from nominal
values that don't in fact reflect the true settings of the mangets.
Objective: make steering set the values of corrector magnets as changes
from their extant values at the time of the implementation of the solution
(when the user actually hits TRIM), rather that as changes from values
acquired from the database when steering was initialized.