Implementing proper treatment of vector valued data

[BenjaminRodenberg]

For testing of the functionality use the structure-structure coupling tutorial proposed in precice/tutorials#27. This PR closes #26 if merged.

What we currently have

Do RBF interpolation on every component of vector field.

fenics-adapter/fenicsadapter/fenicsadapter.py

Lines 63 to 64 in 02e00b7

	elif self.isVectorValues():
	f = Rbf(self._coords_x, self._coords_y, self._vals[:,dim_no].flatten()) # extract dim_no element of each vector

called in eval

fenics-adapter/fenicsadapter/fenicsadapter.py

Lines 81 to 87 in 02e00b7

	def eval(self, value, x): # overloaded function
	"""
	Overrides UserExpression.eval(). Called by Expression(x_coord). handles
	scalar- and vector-valued functions evaluation.
	"""
	for i in range(self._vals.ndim):
	value[i] = self.rbf_interpol(x,i)

Check case SCALAR and VECTOR

New functions implemented. Can be used to determine whether vector or scalar data has to be communicated via preCICE

fenics-adapter/fenicsadapter/fenicsadapter.py

Lines 322 to 325 in 1412a6f

	if self.function_type(write_field) is FunctionType.SCALAR: #write_field.value_rank() == 0:
	self._interface.write_block_scalar_data(self._write_data_id, self._n_vertices, self._vertex_ids, self._write_data)
	elif self.function_type(write_field) is FunctionType.VECTOR:
	self._interface.write_block_vector_data(self._write_data_id, self._n_vertices, self._vertex_ids, self._write_data.ravel())

Tested read_block_vector_data and write_block_vector_data

Open ToDo's

• continue implementation of vector data support in advance
• test with structure-structure coupling tutorial proposed in Tutorial for Structure/Structure coupling with FEniCS tutorials#27

[BenjaminRodenberg]

I think that this PR is pretty much addressed by the current featureset on master. @IshaanDesai can you check it and close the PR (and issue #26), if everything is fine?

[IshaanDesai]

Implementation of treatment of vector valued data is already being handled in #47 and #46 according to the newer code design of the adapter. Merging this PR is of no significance due to significant changes in the adapter design. Tutorial case: precice/tutorials#27 will be handled at a later point of time as indicated in the comments there.