USER MANUAL
SYNOPSIS
PTC_KNOB,
elementname = [s, none] ,
kn = [i, {-1}],
ks = [i, {-1}],
exactmatch = [l, true, true] ;
Description
Sets knobs in PTC calculations (currently ony in PTC_TWISS, PTC_NORMAL will follow).
Knobs appear as the additional parameters of the phase space. Twiss functions are then obtained
as functions of these parameters (Taylor series).
Also map elements might be stored as functions of knobs, see
ptc_select command description to lear how to
request given element to be stored as a Taylor series.
The parametric results can be further
- written to a file with ptc_printparametric.
- plotted and studied using rviewer command (rplot plugin).
- used to obtain very quickly approximate values of lattice functions for given values of knobs
(ptc_setknobvalue).
This feature is the foundation of a fast matching alorithm with PTC.
Example
dog leg chicane :
Dipolar components of both rbends and dipolar and quadrupolar components of the focusing quads set as knobs.
Some first and second order map coefficients set to be stored as parametric results.
ptc_twiss command is performed and the parametric results are written to files in two formats.
dog leg chicane :
Knobs values are matched to get requested lattice functions.
Command parameters and switches
- elementname
-
string in range format,
Specifies name of the element containing the knob(s) to be set.
- kn,ks
-
list of integers,
Defines which order
- exactmatch
-
-
logical, default true, if value explicitly not specified then true
Normally a knob is a property of a single element in a layout.
The specified name must match 1:1 to an element name. This is the case
when exactmatch is true.
Knobs might be alos set to all family of elements. In such case
the exactmatch switch must be false. A given order field component of all the elements
that name starts with the name specified by the user become a single knob.
- initial
-
_
