int sglfdback2(float ***mig1, float **mig2, float ***fwf, float **localrec, bool verb, bool wantwf, sf_file Ftmpbwf)
{
float **txxn1, **txxn0, **vxn1, **vxn0, **vzn1, **vzn0;
float **sill, **ccr, ***bwf;
int wfit, htau;
float tau;
sill=sf_floatalloc2(nz, nx);
ccr=sf_floatalloc2(nz, nx);
bwf=sf_floatalloc3(nz, nx, wfnt);
zero2(sill, nz, nx);
zero2(ccr, nz, nx);
zero3(mig1, nz, nx, ntau);
txxn1=sf_floatalloc2(nzb, nxb);
txxn0=sf_floatalloc2(nzb, nxb);
vxn1=sf_floatalloc2(nzb, nxb);
vxn0=sf_floatalloc2(nzb, nxb);
vzn1=sf_floatalloc2(nzb, nxb);
vzn0=sf_floatalloc2(nzb, nxb);
zero2(txxn1, nzb, nxb);
zero2(txxn0, nzb, nxb);
zero2(vxn1, nzb, nxb);
zero2(vxn0, nzb, nxb);
zero2(vzn1, nzb, nxb);
zero2(vzn0, nzb, nxb);
zero2(txxn1x, nzb, nxb);
zero2(txxn1z, nzb, nxb);
zero2(txxn0x, nzb, nxb);
zero2(txxn0z, nzb, nxb);
wfit=wfnt-1;
for(it=nt-1; it>=0; it--){
if(verb) sf_warning("Backward it=%d/%d;", it+1, nt);
#ifdef _OPENMP
#pragma omp parallel for private(ix,iz)
#endif
for(ix=nfd+pmlsize; ix<nfd+pmlsize+nx; ix++){
for(iz=nfd+pmlsize; iz<nfd+pmlsize+nz; iz++){
txxn0[ix][iz]=txxn1[ix][iz]+dt*bc11[ix][iz]*(ldx(vxn1, ix-1, iz) +ldz(vzn1, ix, iz-1));
}
}
pml_txxb(txxn0, vxn1, vzn1);
#ifdef _OPENMP
#pragma omp parallel for private(ix)
#endif
for(ix=0; ix<ng; ix++){
txxn0[ix*ginv+pmlsize+nfd][pmlsize+nfd+gp]+=localrec[ix][it];
}
#ifdef _OPENMP
#pragma omp parallel for private(ix,iz)
#endif
for(ix=nfd+pmlsize; ix<nfd+pmlsize+nx; ix++){
for(iz=nfd+pmlsize; iz<nfd+pmlsize+nz; iz++){
vxn0[ix][iz]=vxn1[ix][iz]+dt/bdenx[ix][iz]*ldx(txxn0, ix, iz);
vzn0[ix][iz]=vzn1[ix][iz]+dt/bdenz[ix][iz]*ldz(txxn0, ix, iz);
}
}
pml_vxzb(vxn1, vzn1, vxn0, vzn0, txxn0);
transp=txxn1; txxn1=txxn0; txxn0=transp;
transp=vxn1; vxn1=vxn0; vxn0=transp;
transp=vzn1; vzn1=vzn0; vzn0=transp;
if(it%wfinv==0){
for(ix=0; ix<nx; ix++)
for(iz=0; iz<nz; iz++){
bwf[wfit][ix][iz]=txxn0[ix+pmlsize+nfd][iz+pmlsize+nfd];
ccr[ix][iz]+=fwf[wfit][ix][iz]*bwf[wfit][ix][iz];
sill[ix][iz]+=fwf[wfit][ix][iz]*fwf[wfit][ix][iz];
}
wfit--;
}
} //end of it
if(verb) sf_warning(".");
for(itau=0; itau<ntau; itau++){
tau=itau*dtau+tau0;
htau=tau/wfdt;
for(it=abs(htau); it<wfnt-abs(htau); it++){
for(ix=0; ix<nx; ix++){
for(iz=0; iz<nz; iz++){
mig1[itau][ix][iz]+=fwf[it+htau][ix][iz]*bwf[it-htau][ix][iz];
}
}
}//end of it
} // end of itau
for(ix=0; ix<nx; ix++){
for(iz=0; iz<nz; iz++){
mig2[ix][iz]=ccr[ix][iz]/(sill[ix][iz]+SF_EPS);
}
}
if(wantwf) sf_floatwrite(bwf[0][0], wfnt*nx*nz, Ftmpbwf);
return 0;
}
int sglfdback2(float **img1, float **img2, float ***wavfld, float **rcd,
bool verb, bool wantwf, float **den, float **c11,
geopar geop, srcpar srcp, pmlpar pmlp, sf_file Ftmpbwf)
/*< staggered grid lowrank FD backward propagation + imaging >*/
{
/*caculate arrays*/
float **txxn1, **txxn0, **vxn1, **vzn1, **vxn0, **vzn0;
float **denx, **denz;
float **sill, **ccr;
/*grid index*/
int nx, nz, nt, ix, iz, it, gn, ginter;
int nxb, nzb, snpint;
int gp;
float dt, dx, dz;
int pmlout, marg;
bool freesurface;
/* tmp variable */
int wfit;
nx = geop->nx;
nz = geop->nz;
nxb = geop->nxb;
nzb = geop->nzb;
dx = geop->dx;
dz = geop->dz;
gp = geop->gp;
gn = geop->gn;
ginter= geop->ginter;
snpint = geop->snpint;
nt = srcp->nt;
dt = srcp->dt;
pmlout = pmlp->pmlout;
freesurface = pmlp->freesurface;
marg = getmarg();
denx = sf_floatalloc2(nzb, nxb);
denz = sf_floatalloc2(nzb, nxb);
sill = sf_floatalloc2(nz, nx);
ccr = img1;
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix = 0; ix < nxb; ix++) {
for ( iz= 0; iz < nzb; iz++) {
denx[ix][iz] = den[ix][iz];
denz[ix][iz] = den[ix][iz];
}
}
/*den[ix+1/2][iz]*/
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for ( ix = 0; ix < nxb-1; ix++) {
for (iz = 0; iz < nzb; iz++) {
denx[ix][iz] = (den[ix+1][iz] + den[ix][iz])*0.5;
}
}
/*den[ix][iz+1/2]*/
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for ( ix = 0; ix < nxb; ix++) {
for (iz = 0; iz < nzb-1; iz++) {
denz[ix][iz] = (den[ix][iz+1] + den[ix][iz])*0.5;
}
}
txxn1 = sf_floatalloc2(nzb, nxb);
txxn0 = sf_floatalloc2(nzb, nxb);
vxn1 = sf_floatalloc2(nzb, nxb);
vzn1 = sf_floatalloc2(nzb, nxb);
vxn0 = sf_floatalloc2(nzb, nxb);
vzn0 = sf_floatalloc2(nzb, nxb);
init_pml(nz, nx, dt, marg, pmlp);
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix = 0; ix < nxb; ix++) {
for (iz = 0; iz < nzb; iz++) {
txxn1[ix][iz] = 0.0;
}
}
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix = 0; ix < nxb; ix++) {
for (iz = 0; iz < nzb; iz++) {
txxn0[ix][iz] = 0.0;
}
}
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix = 0; ix < nxb; ix++) {
for (iz = 0; iz < nzb; iz++) {
vxn1[ix][iz] = 0.0;
}
}
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix = 0; ix < nxb; ix++) {
for (iz = 0; iz < nzb; iz++) {
vxn0[ix][iz] = 0.0;
}
}
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix = 0; ix < nxb; ix++) {
for (iz = 0; iz < nzb; iz++) {
vzn1[ix][iz] = 0.0;
}
}
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix = 0; ix < nxb; ix++) {
for (iz = 0; iz < nzb; iz++) {
vzn0[ix][iz] = 0.0;
}
}
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix = 0; ix < nx; ix++) {
for (iz = 0; iz < nz; iz++) {
sill[ix][iz] = 0.0;
}
}
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix = 0; ix < nx; ix++) {
for (iz = 0; iz < nz; iz++) {
ccr[ix][iz] = 0.0;
}
}
/*Main loop*/
wfit = (int)(nt-1)/snpint;
for (it = nt-1; it>=0; it--) {
if (verb) sf_warning("Backward it=%d/%d;", it, nt-1);
/*Stress*/
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix = marg+pmlout; ix < nx+marg+pmlout; ix++) {
for ( iz = marg+pmlout; iz < nz+marg+pmlout; iz++) {
txxn0[ix][iz] = txxn1[ix][iz] + dt*c11[ix][iz]*(ldx(vxn1, ix-1, iz) + ldz(vzn1, ix, iz-1));
}
}
/*Stress PML */
pml_txxb(txxn0, vxn1, vzn1, c11, ldx, ldz, freesurface);
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix=0; ix<gn; ix++) {
txxn0[ix*ginter+pmlout+marg][pmlout+marg+gp] = rcd[ix][it];
}
/*velocity*/
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix = marg+pmlout; ix < nx+pmlout+marg; ix++ ) {
for (iz = marg+pmlout; iz < nz+pmlout+marg; iz++) {
vxn0[ix][iz] = vxn1[ix][iz] + dt/denx[ix][iz]*ldx(txxn0, ix, iz);
vzn0[ix][iz] = vzn1[ix][iz] + dt/denz[ix][iz]*ldz(txxn0, ix, iz);
}
}
/*Velocity PML */
pml_vxzb(vxn1, vzn1, vxn0, vzn0, txxn0, denx, denz, ldx, ldz, freesurface);
/*n1 -> n0*/
time_step_exch(txxn1, txxn0, it);
time_step_exch(vxn1, vxn0, it);
time_step_exch(vzn1, vzn0, it);
pml_tstep_exchb(it);
if ( wantwf && it%snpint == 0 ) {
for ( ix = 0; ix < nx; ix++)
sf_floatwrite(txxn0[ix+pmlout+marg]+pmlout+marg, nz, Ftmpbwf);
}
if (it%snpint == 0 ) {
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix=0; ix<nx; ix++) {
for (iz=0; iz<nz; iz++) {
ccr[ix][iz] += wavfld[wfit][ix][iz]*txxn0[ix+pmlout+marg][iz+pmlout+marg];
}
}
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix=0; ix<nx; ix++) {
for (iz=0; iz<nz; iz++) {
sill[ix][iz] += wavfld[wfit][ix][iz]*wavfld[wfit][ix][iz];
}
}
wfit--;
}
} /*Main loop*/
if (verb) sf_warning(".");
#ifdef _OPENMP
#pragma omp parallel for private(ix, iz)
#endif
for (ix=0; ix<nx; ix++) {
for (iz=0; iz<nz; iz++) {
img2[ix][iz] = ccr[ix][iz]/(sill[ix][iz]+SF_EPS);//
}
}
return 0;
}
