- description: Converts data of the form Bρ(z,ϕ) into a set of generalized gradients  for
use with elegant’s BGGEXP element.
computeGeneralizedGradients -input filename -output rootname -mainHarmonic
integer -nHarmonics integer [-allHarmonics 1]
- input — Give the name of the input file, which must be an SDDS file having two
columns and two parameters. The columns are phi and Br, giving respectively the polar
angle in radians and the radial magnetic field in Tesla. Each page should have the
same number of rows n. The phi values are assumed to be equispaced starting at 0
and ending at 2π(1 - 1∕n). The pages are labeled by the parameter z, which gives the
longitudinal coordinate in meters for the data on that page. These z values are assumed
to be equispaced and to cover the entire length of the magnet, starting and ending well
outside the magnet. (For periodic systems, the onePeriod option may be appropriate.
See below.) Finally, a parameter R must exist that gives the radius in meters for the Br
- output — Give the root name for the output files. The main output file, which
has extension ggrad and is used directly with the BGGEXP element, will contain the
generalized gradients for the normal (non-skew) components of the magnetic field. Each
page corresponds to a different harmonic.
- mainHarmonic — The main harmonic of the field, where 2 is quadrupole, 3 is sextupole,
etc. For fields with several designed-in harmonics, use the lowest, and see the entry for
- nHarmonics — The number of harmonics to include.
- allHarmonics — Normally, only allowed harmonics of the main harmonic are included.
However, if the magnet has several main harmonics (e.g., a combined-function
quadrupole and sextupole), this may be inappropriate. In that case, use this option to
force use of all harmonics greater than the given main harmonic.
- authors: M. Borland, R. Lindberg (ANL/APS).