def tendencies_nonlin(self, variables=None, old=None):
"""Return a null SetOfVariables object."""
if old is None:
tendencies = SetOfVariables(
like=self.state.state_phys, info="tendencies_nonlin"
)
else:
tendencies = old
tendencies.initialize(value=0.0)
return tendencies
def tendencies_nonlin(self, variables=None, old=None):
r"""Compute the nonlinear tendencies.
This function has to be overridden in a child class.
Returns
-------
tendencies_fft : :class:`fluidsim.base.setofvariables.SetOfVariables`
An array containing only zeros.
"""
if old is None:
tendencies = SetOfVariables(like=self.state.state_spect)
else:
tendencies = old
tendencies.initialize(value=0.0)
return tendencies