Remove duplicate tabulate functions

[mscroggs]

Curently there is tabulate that returns a matrix, and tabulate_m that directly acts on memory

basix/cpp/basix/finite-element.h

Lines 267 to 316 in e2137c8

	/// Compute basis values and derivatives at set of points.
	///
	/// @note The version of `FiniteElement::tabulate` with the basis data
	/// as an out argument should be preferred for repeated call where
	/// performance is critical
	///
	/// @param[in] nd The order of derivatives, up to and including, to
	/// compute. Use 0 for the basis functions only.
	/// @param[in] x The points at which to compute the basis functions.
	/// The shape of x is (number of points, geometric dimension).
	/// @return The basis functions (and derivatives). The shape is
	/// (derivative, point, basis fn index, value index).
	/// - The first index is the derivative, with higher derivatives are
	/// stored in triangular (2D) or tetrahedral (3D) ordering, i.e. for
	/// the (x,y) derivatives in 2D: (0,0), (1,0), (0,1), (2,0), (1,1),
	/// (0,2), (3,0)... The function basix::indexing::idx can be used to find the
	/// appropriate derivative.
	/// - The second index is the point index
	/// - The third index is the basis function index
	/// - The fourth index is the basis function component. Its has size
	/// one for scalar basis functions.
	xt::xtensor<double, 4> tabulate(int nd, const xt::xarray<double>& x) const;
	/// Compute basis values and derivatives at set of points.
	///
	/// @note This function is designed to be called at runtime, so its
	/// performance is critical.
	///
	/// @param[in] nd The order of derivatives, up to and including, to
	/// compute. Use 0 for the basis functions only.
	/// @param[in] x The points at which to compute the basis functions.
	/// The shape of x is (number of points, geometric dimension).
	/// @param [out] basis Memory location to fill. It must be allocated
	/// with shape (num_derivatives, num_points, num basis functions,
	/// value_size). The function `FiniteElement::tabulate_shape` can be
	/// used to get the required shape.
	/// - The first index is the derivative, with higher derivatives are
	/// stored in triangular (2D) or tetrahedral (3D) ordering, i.e. for
	/// the (x,y) derivatives in 2D: (0,0), (1,0), (0,1), (2,0), (1,1),
	/// (0,2), (3,0)... The function basix::indexing::idx can be used to
	/// find the appropriate derivative.
	/// - The second index is the point index
	/// - The third index is the basis function index
	/// - The fourth index is the basis function component. Its has size
	/// one for scalar basis functions.
	///
	/// @todo Remove all internal dynamic memory allocation, pass scratch
	/// space as required
	void tabulate(int nd, const xt::xarray<double>& x,
	xt::xtensor<double, 4>& basis) const;

The tabulate returning a matrix should be removed, then the memory version can be used from pybind to make the Python version that returns a matrix

See also #310.