message: Simplify basis rescaling code slightly, adding const
diff: @@ -318,12 +318,9 @@ private:
  inline Eigen::MatrixXf rescale_pca_basis(const Eigen::MatrixXf& orthonormal_basis,
  const Eigen::VectorXf& eigenvalues)
  {
  - using Eigen::MatrixXf;
  - MatrixXf rescaled_basis(orthonormal_basis.rows(),
  + Eigen::MatrixXf rescaled_basis(orthonormal_basis.rows(),
  orthonormal_basis.cols()); // empty matrix with the same dimensions
  - MatrixXf sqrt_of_eigenvalues =
  - eigenvalues.array().sqrt(); // using eigenvalues.sqrt() directly gives a compile error. These are all
  - // Eigen::Array functions? I don't think we copy here, do we?
  + const Eigen::VectorXf sqrt_of_eigenvalues = eigenvalues.array().sqrt();
  // Rescale the basis: We multiply each eigenvector (i.e. each column) with the square root of its
  // corresponding eigenvalue
  for (int basis = 0; basis < orthonormal_basis.cols(); ++basis)
  @@ -346,14 +343,10 @@ inline Eigen::MatrixXf rescale_pca_basis(const Eigen::MatrixXf& orthonormal_basi
  inline Eigen::MatrixXf normalise_pca_basis(const Eigen::MatrixXf& rescaled_basis,
  const Eigen::VectorXf& eigenvalues)
  {
  - using Eigen::MatrixXf;
  - MatrixXf orthonormal_basis(rescaled_basis.rows(),
  + Eigen::MatrixXf orthonormal_basis(rescaled_basis.rows(),
  rescaled_basis.cols()); // empty matrix with the same dimensions
  - Eigen::VectorXf one_over_sqrt_of_eigenvalues =
  - eigenvalues.array()
  - .sqrt()
  - .inverse(); // Eigen added Array::rsqrt() in 3.3, switch back to that eventually
  - // De-normalise the basis: We multiply each eigenvector (i.e. each column) with 1 over the square root of
  + const Eigen::VectorXf one_over_sqrt_of_eigenvalues = eigenvalues.array().rsqrt();
  + // "Normalise" the basis: We multiply each eigenvector (i.e. each column) with 1 over the square root of
  // its corresponding eigenvalue
  for (int basis = 0; basis < rescaled_basis.cols(); ++basis)
  {
  