Program sfavvvdwe3d | 3D acoustic variable-velocity variable-density time-domain FD modeling 
[SYNOPSIS]
sfavvvdwe3d < Fwav.rsf vel=Fvel.rsf den=Fden.rsf sou=Fsou.rsf rec=Frec.rsf > Fdat.rsf wfl=Fwfl.rsf verb=n free=n dabc=n adj=n snap=y nb=NOP jsnap=1 dpt=n
[COMMENTS]

The code uses a standard second-order stencil in time.
The coefficients of the spatial stencil are computed
by matching the transfer function of the 6-point discretized
first-derivative operator to the ideal response.

The code implements the linearized operator obtained from the
system of first-order PDEs parametrized in incompressibility and density

dv/dt = - 1./rho * grad(p)
dp/dt = - K * div(v)

where
rho  : density
K    : incompressibility
div  : divergence operator
grad : gradient  operator
p,v    : pressure and particle velocity wavefields

The models supplied by the user are wave speed and density, the code performs
the conversion internally to buoyancy (inverse density) and incompressibility.

Author: Francesco Perrone
Date: November 2020

[PARAMETERS]
bool    | adj | =n |  [y/n] | 	Adjointness  
bool    | dabc | =n |  [y/n] | 	Absorbing BC 
file    | den | = |   | 	auxiliary input file name
bool    | dpt | =n |  [y/n] | 	run dot product test 
bool    | free | =n |  [y/n] | 	Free surface 
int     | jsnap | =1 |   | 	undersampling factor for the wavefields
int     | nb | =NOP |   | 	thickness of the absorbing boundary: NOP is the width of the FD stencil 
file    | rec | = |   | 	auxiliary input file name
bool    | snap | =y |  [y/n] | 	wavefield snapshots 
file    | sou | = |   | 	auxiliary input file name
file    | vel | = |   | 	auxiliary input file name
bool    | verb | =n |  [y/n] | 	Verbosity    
file    | wfl | = |   | 	auxiliary output file name
[DIRECTORY]
user/fperrone
