This module provides a basis that is suitable for the calculation of low-frequency normal modes. The basis is derived from vector fields whose components are stationary waves in a box surrounding the system. For a description see [Hinsen1998].
Returns the number of basis vectors in a FourierBasis for the given universe and cutoff.
Returns an estimate for the cutoff that will yield a basis of nmodes vectors for the given universe. The two return values are the cutoff and the precise number of basis vectors for this cutoff.
To be used with MMTK.NormalModes.SubspaceNormalModes.
Constructor: FourierBasis(universe, cutoff)
the universe for which the basis will be used
the wavelength cutoff. A smaller value means a larger basis.
A FourierBasis object behaves like a sequence of MMTK.ParticleVector objects. The vectors are not orthonormal, because orthonormalization is handled automatically by the class MMTK.NormalModes.SubspaceNormalModes.