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##

linear_chromatic_tracking_setup

- type: setup command.
- function: define chromatic variation of beta functions, tunes, etc. for using in
fast linear-chromatic tracking

&linear_chromatic_tracking_setup
double nux[4] = {-1, 0, 0, 0};
double betax[2] = {1.0, 0.0};
double alphax[2] = {0.0, 0.0};
double etax[2] = {0.0, 0.0};
double etapx[2] = {0.0, 0.0};
double nuy[4] = {-1, 0, 0, 0};
double betay[2] = {1.0, 0.0};
double alphay[2] = {0.0, 0.0};
double etay[2] = {0.0, 0.0};
double etapy[2] = {0.0, 0.0};
double alphac[2] = {0.0, 0.0};
&end

`nux`

-- Provide the horizontal tune plus its first three chromatic derivatives, i.e.,
,
, and
.
`betax`

-- Provide the horizontal beta function plus its chromatic derivative.
`alphax`

-- Provide the horizontal alpha function plus its chromatic derivative.
`etax`

-- Provide the first- and second-order horizontal dispersion:
.
`etapx`

-- Provide the first- and second-order horizontal dispersion slope.
`alphac`

-- Provide the first and second-order momentum compaction. N.B: if you are tracking
with an rf cavity, be sure that your lattice length equal to the actual circumference. See the example below.

An example of a good lattice for use with this feature is the following:

! Actual length of the ring
d0: drift,l=30.6667
! Actual rf voltage and frequency
rf: rfca,l=0,volt=30e3,phase=180,freq="c_mks 30.6667 /"
w1: watch,filename="%s.w1",mode="centroid"
ring: line=(d0,rf,w1)

Any additional elements (e.g,. wakes or impedances) should follow d0. No other elements represented by a matrix
should be present!
An alternative for using this command is to use `ILMATRIX` elements in the lattice definition. This is more
flexible, since one can include tune shifts with amplitude.

Robert Soliday
2014-03-21