iFunc_Sqw2D: create class

[farhi]

and allow methods:

• Bosify
• deBosify
• dos
• thermochemistry
• incoherent
• scattering_cross_section
• Sab
• moments
• structure_factor
• dynamic_range
• symmetrize
• multi_phonons
• ...

to produce an transformed iFunc suited for S(q,w) models. Could support 1D S(q=cte, w) models.

[farhi]

Considered to be effective. Some methods are still missing, but this will be done gradually.

[farhi]

Should also add a DebyeWaller Q dependency exp(-q2u2) Model

[farhi]

And QENS models from LAMP

• http://lamp.mccode.org/pub/cs/lamp_runtimes/Misc/Others/STR_FIT_QENS_models.pdf

[farhi]

methods that change the type (q,w) -> something else (iFunc 1D)

• scattering_cross_section(Ei_min, Ei_max, Ei_n, Mass) -> 1D iFunc(Ei) -> new axis !!
• thermochemistry(T) -> 1D iFunc array ?

And all these are done or wont-do:

• moments(M,T, classical) -> 1D iFunc array DONE
• structure_factor/sq -> 1D iFunc DONE
• dos/gdos(T, DW, method) -> 1D iFunc(w) DONE
• muphocor(T, amasi, sigi, conci) -> 1D array WONT DO
• incoherent(q, T, m, n, DW, vDOS ) DONE
• multi_phonons -> 1D(w) -> incoherent can be used with higher order terms DONE
• dynamic_range(Ei, angle_min, angle_max) DONE
• coherent (iData sq or d-spacing value) DONE
• Sqw2ddcs(Ei) DONE
• ddcs2Sqw(Ei) WONT DO usually not needed. Models are usually in S(q,w)
• Sab(M,T) DONE
• qw2phiw(lambda) DONE
• qw2phit(lambda) DONE
• qw2qt(lambda, chwidth, dist) WONT DO not needed, qw2phit and qw2phiw are usually enough

[farhi]

Only remains methods for which the axis is a parameter of inner model, e.g. Ei or T. This could be achieved with a scan of these parameters, e.g.

• signal = feval(model, struct_p.Ei=[values])
• x = [values];