PTC_SELECT_MOMENT

SYNOPSIS

PTC_SELECT_MOMENT, 
table      = [s, none, none], 
column     = [s, none, none], 
moments   = [s, none] , 
moments   = [i, {0}] , 
parametric = [l, false, true], 

a) Stored in a user specified table and column.

b) Stored as a function (taylor series) of knobs, if any is defined. Than, parametric switch should be set to true.

Both a) and b) can be joined in one command.

moment_s

list of coma separated strings composed of up to 6 digits

Defines moment of the polynomial in PTC nomenclature. String 'ijklmn' (i,j,k,l,m,n are digits ) defines <xⁱp_x^jy^kp_y^l ΔT^m(Δp/p)ⁿ>. For example, moments=1000000 defines <x¹>

Note that for input we always use MAD-X notation where dp/p is always the 6th coordinate. (Internaly PTC dp/p is the 5th coordinate. We perform automatic conversion that is transparent for the user.) As the consequence RMS in dp/p is always defined as 000002, even in 5D case.

This notations allows to define more then one moment with one command. In this case, the corresponding column names are as the passed strings with "mu" prefix. However, they are always extended to 6 digits, i.e. the trailing 0 are automatically added. For example, if specified moments=2, the column name is mu200000.

This method does not allow to pass bigger numbers then 9. If you need to define such a moment, use the command switch below.

moment

list of up to 6 coma separated integers,

Defines a moment. For example: moment=2 defines <x²> , moment=0,0,2 : <y²>, moment=0,14,0,2 : <px¹⁴py²>, etc.

table

string, default "moments"

Specifies name of the table where the calculated moments should be stored.

column

string

Ignored if moments is specified. Defines name of the column where values should be stored. If not specified then it is automatically generated from moment the definition <xⁱp_x^jy^kp_y^l ΔT^m(Δp/p)ⁿ> => mu_i_j_k_l_m_n (numbers separated with underscores).

parametric

logical, default false, if value explicitly not specified then true

If it is true, and any knobs are defined the map element is stored as the parametric result.