module hypotenuse {                                   # Normal moveout
real ::  t0, dt, xs
#%  _init( t0, dt, xs)
#%  _lop(   zz, tt)
integer   it, iz
real t, zsquared
do it= 1, size(tt) {  t = t0 + dt*(it-1)
        zsquared =  t * t - xs * xs
        if ( zsquared >= 0.) {  iz = 1.5 + (sqrt( zsquared) - t0) /dt
                if ( iz > 0 ) {
			  if( adj)    zz(iz) +=  tt(it)
			  else        tt(it) +=  zz(iz)
                          }
                }
        }
}