subroutine stack1( adj, add, slow,     t0,dt, x0,dx, nt,nx, stack, gather)
integer ix,        adj, add,                         nt,nx
real     x,                  slow(nt), t0,dt, x0,dx,   stack(nt), gather(nt,nx)
call adjnull(      adj, add,                           stack,nt,  gather,nt*nx)
do ix= 1, nx {
	x = x0 + dx * (ix-1)
	call nmo1( adj, 1, slow, x, t0,dt, nt, stack, gather(1,ix))
	}
return; end