Home > Applications > Horace > @d3d > disp2sqw_eval.m

iFit/disp2sqw_eval

PURPOSE ^

Calculate sqw for a model scattering function

SYNOPSIS ^

function wout=disp2sqw_eval(win,varargin)

DESCRIPTION ^

 Calculate sqw for a model scattering function

   >> wout = disp2sqw_eval(win,dispreln,pars,fwhh,opt)

 Input:
 ------
   win         Dataset, or array of datasets, that provides the axes and points
              for the calculation

   dispreln    Handle to function that calculates the dispersion relation w(Q) and
              spectral weight, s(Q)
              Must have form:
                   [w,s] = dispreln (qh,qk,ql,p)
               where
                   qh,qk,ql    Arrays containing the coordinates of a set of points
                              in reciprocal lattice units
                   p           Vector of parameters needed by dispersion function 
                              e.g. [A,js,gam] as intensity, exchange, lifetime
                   w           Array of corresponding energies, or, if more than
                              one dispersion relation, a cell array of arrays.
                   s           Array of spectral weights, or, if more than
                              one dispersion relation, a cell array of arrays.

              More general form is:
                   [w,s] = dispreln (qh,qk,ql,p,c1,c2,..)
                 where
                   p           Typically a vector of parameters that we might want 
                              to fit in a least-squares algorithm
                   c1,c2,...   Other constant parameters e.g. file name for look-up
                              table.

   pars        Arguments needed by the function. Most commonly, a vector of parameter
              values e.g. [A,js,gam] as intensity, exchange, lifetime. If a more general
              set of parameters is required by the function, then
              package these into a cell array and pass that as pars. In the example
              above then pars = {p, c1, c2, ...}

   fwhh        Full-width half-height of Gaussian broadening to dispersion relation(s)

   'all'       [option] Requests that the calculated sqw be returned over
              the whole of the domain of the input dataset. If not given, then
              the function will be returned only at those points of the dataset
              that contain data.
               Applies only to input with no pixel information - it is ignored if
              full sqw object.

   'ave'       [option] Requests that the calculated sqw be computed for the
              average values of h,k,l of the pixels in a bin, not for each
              pixel individually. Reduces cost of expensive calculations.
               Applies only to the case of sqw object with pixel information - it is
              ignored if dnd type object.

 Output:
 -------
   wout        Output dataset or array of datasets

CROSS-REFERENCE INFORMATION ^

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