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1. calculate relative to design values using a dimensionless "LEM error", i.e. the ratio of the live momentum profile to the design profile

   Latex
   \sigma[ BDES_{designLEM}(s) = \left \frac{E_{live}(s) / }{E_{design}(s) BDES_{LEM} = \sigma_{design}(s) *\right BDES_{design}

2.  calculate relative to design values using design multipole coefficients (lcls style)
   1. get design multipole coefficients (k0_des, k1_des for bends/quads), and (effective) magnet lengths l_eff from the model

   2. calculate the rigidity like so live magnetic rigidity & required field strength (where E_live is in GeV) 

      Latex
      \[ B\rho(s) = \frac{E_{live}(s)}{299.792458*10^4} \[ BDES_{LEM} = B\rho * k_{design} * l_{eff}

3. calculate

   new magnet BDESes

   relative to extant settings

   Latex
   \[ BDES_{LEM} =

   B\rho * k_{design} * l_{eff}

   by default, matching quads should scale relative to their extant values, since they are correcting the optics for variations from design

   Latex
   \sigma_{extant}(s) = \left \frac{E_{live}(s) / }{E_{live, previousold}(s) BDES_{LEM} = \sigma_{extant}(s)\right * BDES_{extant}

   1. note: requires a previously implemented BLEM
   2. matching quads should always scale from extant values

F2 Live Model Server

The live model server runs its own BmadLiveModel, and periodically writes live model data for NTTables accessible on the controls system via EPICS PVAccess. The code for the live model itself is relatively simple, and is derived from the lcls_live_model server.

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