Introduction

The source code of Afivo is located in different folders:

Folder	Description
src	Contains the source code of the framework
examples	Contains example programs
documentation	Contains the Doxygen documentation
tests	Contains some simple tests of the framework
`external_libraries`	After compilation, contains the Silo library
`misc_files`	Miscellaneous and old files (could be removed)

The src folder

The folder src contains the source of Afivo, split over several modules. The m_aX_[...].f90 files contain code for both the 2D and 3D version. These files are automatically translated to 2D and 3D version (m_a2_[...].f90 and m_a3_[...].f90), as described below. Modifications should therefore be made in the m_aX_[...].f90 files.

List of modules and prefixes

The table below contains a brief description of Afivo's modules. The a2_ modules have 3D equivalents with the prefix a3_.

Module name	Prefix	Description
`m_afivo_types`	`af_`	Dimension-independent types and constants
`m_a2_core`	`a2_`	Core routines to construct and refine the mesh
`m_a2_types`	`a2_`	Dimension-dependent types and routines related to indexing
`m_a2_utils`	`a2_`	All kinds of different 'helper' routines for Afivo
`m_a2_output`	`a2_write_`	Routines for writing output
`m_a2_ghostcell`	`a2_gc_`	Routines for filling ghost cells
`m_a2_restrict`	`a2_restrict_`	Routines for restriction (going from fine to coarse values)
`m_a2_prolong`	`a2_prolong_`	Routines for prolongation (going from coarse to fine values)
`m_a2_interp`	`a2_interp_`	Routines for interpolation on the grid
`m_a2_multigrid`	`mg2_`	Multigrid routines and data structures
`m_a2_all`	-	Module that contains all of Afivo

Translating code to 2D/3D

The translation is performed using a couple simple preprocessor rules:

Pattern	Replacement 2D	Replacement 3D
`$D`	2	3
`IJK`	`i, j`	`i, j, k`

To simplify writing loops, the following patterns are defined in cpp_macros_2d.h and cpp_macros_3d.h:

do KJI_DO(a,b)
--->
2D: do j = a, b; do i = a, b
3D: do k = a, b; do j = a, b; do i = a, b

end do; CLOSE_DO
--->
2D: end do; end do
3D: end do; end do; end do

DTIMES(xx)
--->
2D: xx, xx
3D: xx, xx, xx

Furthermore, blocks of code specific for 2D and 3D can be written as:

#if $D == 2
    ...
#elif $D == 3
    ...
#endif