VAMPyR-1.0 (or future) wishlist

[stigrj]

Dear 🎅

Please edit and add new features at will (not saying everything should be implemented for v1):

• More user friendly MRA initialization, e.g. world_size = [-20, 20]**3
• Function plotting (line, surface, cube)
• Function printing, what should be displayed with print(tree)?
• Basis visualization
  • scaling and wavelet functions
  • two-scale relations
  • dilation and translation of functions
• Features to build your own wavelet code
  • extract filter matrices
  • Legendre polynomials
• Tree/grid visualization
  • any ideas?
  • ASCII art for 1D trees?
  • existing Python library?
• Difference plots
  • functions/differences at different resolution levels
  • plot wavelet information content as function of scale
• New operators
  • convolution operator from arbitrary 1D Gaussian expansion (examples?)
  • other 1D operators (e.g. exponential operator for solving the heat equation and Burger's equation, see ABGV)
  • brute-force projection of any kind of non-separable operator?
• Use scikit-build to build: https://scikit-build.readthedocs.io/en/latest/
• Documented test-cases
  • H-atom
  • ZORA
  • generalized poisson
• Interface documentation
• Deep copy
• Generic kernel G(x-y) which takes vector of functions g_i(x) such that G(x) = \sum_i g_i(x)
• Resolve fast vs accurate dilemma for FunctionTree evaluation
• Handling of complex functions (separate trees for Real and Imaginary part)
• Add call function to operators, g_tree = P(f_tree)
• New MWProjector class which enables f_tree = Q(func);

[robertodr]

- [ ] Use scikit-build to build: https://scikit-build.readthedocs.io/en/latest/

[robertodr]

• Operator overloading for most common form of operations. For example:/

   .def("__add__", [](FunctionTree<D>& tree_a, FunctionTree<D>& tree_b) { /* code here */ }, py::is_operator());

[robertodr]

• KAIN and DIIS implementation.