subroutine stoltmod( nz,nt,nx, dz,dt,dx, vel, cftimage, cftdata)
integer iz,it,ix,    nz,nt,nx,    ikz,iw,ikx, nkz,nw,nkx
real	dz,dt,dx, kz0,w0,kx0, dkz,dw,dkx, pi, vel,vhalf, kz,w,kx, signum
complex	cwkx, cftimage(nz,nx), cftdata(nt,nx)
pi = 3.1415926
nkz = nz;	kz0 = -pi/dz;	dkz = 2.*pi/(nz*dz);
nw  = nt;	w0  = -pi/dt;	dw  = 2.*pi/(nt*dt);
nkx = nx;	kx0 = -pi/dx;	dkx = 2.*pi/(nx*dx);
do iw = 1, nw  {	cftdata(  iw,   1) = (0.,0.) }	# zero the Nyquist.
do ikx= 1, nkx {	cftdata(   1, ikx) = (0.,0.) }	# zero the Nyquist.
vhalf = 0.5 * vel
do ikx = 2, nkx {	kx = kx0 + dkx * (ikx-1)
do iw  = 2, nw  {	w  = w0  + dw  * (iw -1)
	kz = w*w/(vhalf*vhalf)-kx*kx
	if(kz >= 0.)	{ kz = - signum( w)*sqrt( kz) }
	else		{ kz = 0. 		      }
	call cinterp1( kz, nkz,kz0,dkz, cftimage(1,ikx), cwkx)
	if( kz != 0.)
		cftdata(iw,ikx) = cwkx
	else
		cftdata(iw,ikx) = 0.
	}}
return; 	end