FFT tutorial documentation

Author: ajnonaka

Docs/source/FFT_Tutorial.rst

@@ -0,0 +1,38 @@
+.. role:: cpp(code)
+   :language: c++
+
+.. role:: fortran(code)
+   :language: fortran
+
+.. _tutorials_fft:
+
+FFT
+==========================
+
+These tutorials demonstrate how to use the amrex::FFT classes to solve for and manipulate Fourier transform data.
+For more information on the amrex::FFT class refer to the AMReX documentation 
+`here <https://amrex-codes.github.io/amrex/docs_html/FFT_Chapter.html>`_.
+
+There are two FFT tutorials, ``Basic`` and ``Poisson``.
+
+.. toctree::
+   :maxdepth: 1
+
+.. _section:fft_tutorial:fft_basic:
+
+Basic
+--------------------------
+
+The tutorial found in ``amrex-tutorials/ExampleCodes/FFT/Basic`` demonstrates how
+to take a forward FFT, manipulate or access the spectral data (in this example by copying the spectral
+data into a :cpp:`MultiFab` for plotfile visualziation) and then taking the inverse FFT.
+
+.. _section:fft_tutorial:fft_pois:
+
+Poisson
+--------------------------
+
+This tutorial: ``amrex-tutorials/ExampleCodes/FFT/Poisson``
+solves a Poisson equation with periodic boundary conditions.  It relies on the :cpp:`AMReX_FFT_Poisson.H`
+routines to solve the equation by using the ``forwardThenBackward`` function which takes the forward and inverse
+transform of the data with spectral data scaling in between as required by the Poisson equation.

Docs/source/index.rst

@@ -45,6 +45,7 @@ sorted by the following categories:
   Conduit Mesh Blueprint for use with the ALPINE Ascent in situ visualization
   and analysis tool.
 - :ref:`EB<tutorials_eb>`  -- Examples of embedded boundaries.
+- :ref:`FFT<tutorials_fft>`  -- Demonstration on how to use the amrex::FFT class for forward/inverse FFT and data manipulation
 - :ref:`FFTW<tutorials_fftw>`  -- FFTW and cuFFT single-rank tutorials.
 - :ref:`ForkJoin<tutorials_forkjoin>` -- Parallel execution and subgrouping of MPI ranks.
 - :ref:`GPU<tutorials_gpu>`  -- Offload work to the GPUs using AMReX tools.
@@ -70,6 +71,7 @@ sorted by the following categories:
    Basic_Tutorial
    Blueprint_Tutorial
    EB_Tutorial
+   FFT_Tutorial
    FFTW_Tutorial
    ForkJoin_Tutorial
    GPU_Tutorial