trying to understand linear elasticity

So, I dug into sfepy/sfepy/terms/termsLinElasticity.py(61)__call__() a bit to try and understand how linear elasticity is being handled:

def __call__( self, diff_var = None, chunk_size = None, **kwargs ): Pdb().set_trace() material, virtual, state = self.get_args( **kwargs ) ap, vg = virtual.get_approximation( self.get_current_group(), 'Volume' )

    shape, mode = self.get_shape( diff_var, chunk_size, ap )
    fargs = self.build_c_fun_args( material, state, ap, vg )

    for out, chunk in self.char_fun( chunk_size, shape ):
        status = self.function( out, *fargs + (chunk, mode) )
        yield out, chunk, status

I think I understand the first line: material, virtual, state = self.get_args( **kwargs ). It seems to extract the material, including its Lame parameters and all that, along with the state. I am not entirely sure what state means:

ipdb> print state Variable:u kind: unknown _order: 0 name: u family: field dual_var_name: v dpn: 3 dof_conns: Struct:dof_conns indx: slice(0, 1062, None) dof_name: u dtype: <type 'numpy.float64'> field: Field:3_displacement step: None eq_map: Struct flags: set([0, 10]) i_dof_max: 1062 key: variable_1 current_ap: None n_dof: 1062 dofs: ['u.0', 'u.1', 'u.2'] data: deque([array([ 0., 0., 0., ..., 0., 0., 0.])]) history: None

Some of those terms make sense. But what are deque and flags? What is the indx used for? Is that to get this node out of the mesh?

But it seems like the real action happens when self.function is called. self.function refers to sfepy/sfepy/terms/extmods/terms.py(166)dw_lin_elastic_iso() which just calls a C function. I am scared that implementing a nonlinear material model will require C programming. I haven't done much C lately.

Ryan