adding ktap on additional elements

[rdemaria]

From @ghislain-roy

indeed KTAP is currently implemented for bends, quadrupoles and sextupoles. I can extend the KTAP mechanism to octupoles and multipoles. Implementing KTAP for the octupoles should be very straightforward. Implementing KTAP for the general thin multipole means adding a single parameter for all components of the multipole. The only issue is to make sure it is taken into account everywhere the multipole components are used. For other elements, remember that KTAP is intended to be used for "tapering circuits”. This parameter makes sense for most magnetic elements but does not make sense for solenoids, kickers, RF cavities, etc.

[ghislain-roy]

Code mostly completed. I now need an example combining taper and makethin, and including octupoles and multipoles, to check that all is working fine. I have already inserted zero-strength octupoles and multipoles in an FCC lattice to check that taper is properly calculated. I would like to further test the usage of taper for octupoles and multipoles.

[ghislain-roy]

Sent an email to Helmut Burkhardt to request a test case.

[rdemaria]

@fscarlier proposed also to change the name 'ktap' in 'ftap' to avoid implying that ktap is in unit of m^-n, while it is unit less.

For me the proposal is fine, if the users of the existing users for tapering agree (@tpersson, @ghislain-roy please comment!)

[ghislain-roy]

I don’t think there can be confusion about ktap when it is properly documented in the manual and a name starting with k does not imply that it is a strength but if anything that it is related to a strength.

And in the proposed ftap, what is the f standing for ?

[rdemaria]

f for factor I believe

[rdemaria]

addressed in f0774f6874973b82eb4d