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calculates symbolic spin wave dispersion


function spectra = spinwavesym(obj, varargin)


 calculates symbolic spin wave dispersion

 spectra = SPINWAVESYM(obj, 'option1', value1 ...)

 Symbolic spin wave dispersion is calculated as a function of reciprocal
 space points. The function can deal with arbitrary magnetic structure and
 magnetic interactions as well as single ion anisotropy and magnetic

 If the magnetic ordering wavevector is non-integer, the dispersion is
 calculated using a coordinate system rotating from cell to cell. In this
 case the Hamiltonian has to fulfill this extra rotational symmetry.

 The method works for incommensurate structures, however the calculated
 omega dispersion does not contain the omega(k+/-km) terms that has to be
 added manually.

 The method for matrix diagonalization is according to R.M. White, PR 139
 (1965) A450. The non-Hermitian g*H matrix will be diagonalised.


 obj           Input structure, sw class object.


 hkl           Symbolic definition of q vector. Default is the general Q
                   hkl = [sym('h') sym('k') sym('l')]
 eig           If true the symbolic Hamiltonian is diagonalised. For large
               matrices (many magnetic atom per unit cell) this might be
               impossible. Set 'eig' to false to output only the quadratic
               Hamiltonian. Default is true.
 tol           Tolerance of the incommensurability of the magnetic
               ordering wavevector. Deviations from integer values of the
               ordering wavevector smaller than the tolerance are
               considered to be commensurate. Default value is 1e-4.
 norm          Whether to produce the normalized eigenvectors. It can be
               impossible for large matrices, in that case set it to
               false. Default is true.
 title         Gives a title string to the simulation that is saved in the


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