attempt to doc Joakim's pyproject.toml system

docs/devnotes.rst

@@ -27,11 +27,11 @@ Developer notes
 
 * The kernel function in spreadinterp is evaluated via piecewise-polynomial approximation (Horner's rule). The code for this is auto-generated in MATLAB, for all upsampling factors. There are two versions supported:
 
-  - 2018--2024 vintage: no explicit SIMD vectorization, C code is generated code for the Horner evaluation loop, by running from MATLAB `gen_all_horner_C_code.m`
+  - 2018--2024 vintage: no explicit SIMD vectorization, C code is generated code for the Horner evaluation loop, by running from MATLAB ``gen_all_horner_C_code.m``
 
-  - post-2024 vintage: explicit SIMD and many other acceleration tricks, and the generated code is a static C++ array of coefficients, and their sizes (`nc` or number of coefficients) for each width `w`. Run from MATLAB `gen_ker_horner_loop_cpp_code.m`
+  - post-2024 vintage: explicit SIMD and many other acceleration tricks, and the generated code is a static C++ array of coefficients, and their sizes (``nc`` or number of coefficients) for each width ``w``. Run from MATLAB ``gen_ker_horner_loop_cpp_code.m``
 
-  See `devel/README` for more details. The ES kernel coefficient and poly approx degree for both of the above are defined in a single location, `devel/get_degree_and_beta.m`, which must match the C++ `setup_spreader()` function.
+  See ``devel/README`` for more details. The ES kernel coefficient and poly approx degree for both of the above are defined in a single location, ``devel/get_degree_and_beta.m``, which must match the C++ ``setup_spreader()`` function.
 
 * Continuous Integration (CI). See files for this in ``.github/workflows/``. It currently tests the default ``makefile`` settings in linux, and three other ``make.inc.*`` files covering OSX and Windows (MinGW). CI does not test build the variant OMP=OFF. The dev should test these locally. Likewise, the Julia wrapper is separate and thus not tested in CI. We have added ``JenkinsFile`` for the GPU CI via python wrappers.
 

docs/install.rst

@@ -467,8 +467,8 @@ Also see https://github.com/flatironinstitute/finufft/issues
 
 .. _install-python:
 
-Building a python interface to a locally compiled library
------------------------------------------------------------------------
+Building a Python interface to a locally compiled library
+---------------------------------------------------------
 
 Recall that the basic user may simply ``pip install finufft``,
 then check it worked via either (if you have ``pytest`` installed)::
@@ -482,31 +482,21 @@ or the older-style eyeball check with::
 which should report errors around ``1e-6`` and throughputs around 1-10 million points/sec.
 
 However, a user or developer may want to build a python wrapper to their locally
-compiled FINUFFT library, perhaps for more speed. We now describe this,
-for all OSes.
-We assume ``python3`` (hence ``pip3``; make sure you have that installed).
+compiled FINUFFT library, perhaps for more speed.
+We now describe this, for all OSes.
+We assume ``python`` (hence ``pip``; make sure you have that installed), at least version 3.8. We now use the modern ``pyproject.toml`` build system,
+which locally compiles (giving you native performance on your CPU).
+For this, run::
 
-First, compile the shared C++ library, via, eg ``make lib -j`` (using the old-style ``makefile``),
-or via::
+  pip install -e python/finufft
 
-  make -p build
-  cd build
-  cmake ..
-  cmake --build . -j
-  cd ..
-
-You may then run::
-
-  pip3 install -e python/finufft
-
-which builds the ``finufft`` Python module, linking to the ``.so``,
-and installs (in editable mode) via pip.
-You will see that the ``finufftc.*.so`` shared object appears in the ``python/finufft/finufft/`` directory.
+which compiles the library from source then makes the ``finufft`` Python module
+and installs (in editable mode). If you see a complaint about missing ``setup.py``, you need a more recent version of pip/python.
 You should then run the above tests. You could also run tests and examples via ``make python``.
 
 An additional performance test you could then do is::
 
-  python3 python/finufft/test/run_speed_tests.py
+  python python/finufft/test/run_speed_tests.py
 
 .. note::