mod_cyMigrate.pyx

from __future__ import division
import numpy as np
cimport numpy as np



cimport cython
@cython.boundscheck(False) # turn off bounds-checking

def cyMigrate(np.ndarray[np.float32_t, ndim=3] data,int nx, int dx,int nz,int dz,float dt,int dcdp,int v,np.ndarray[np.int_t, ndim=1] offsets,int nsamples,int ntrc,int noff, int ioff=0):
    cdef np.ndarray[np.float32_t, ndim=2] R = np.zeros((nx, nz),dtype=np.float32)
    cdef int ix, iz, itrc
    cdef int x, z
    cdef int ksi
    cdef float h, rs, rr, wco, t
    cdef int it
    for ix in range(0, nx):        #loop over discreticized undergroundpoints in x
        x = dx*ix
        for iz in range(1, nz):    #loop over discreticized undergroundpoints in z
            z = dz*iz               #(depth)
            
            for itrc in range(0, ntrc):     #loop over all traces
                ksi = dcdp * itrc           # cdp point
                h = offsets[ioff]/2         # half offset
                rs = np.sqrt( (x - (ksi-h))**2 + z**2)     # distance point-source
                rr = np.sqrt( (x - (ksi+h))**2 + z**2)     # distance point-reviever
    
                wco = ( z/rs * np.sqrt(rs/rr) + z/rr * np.sqrt(rr/rs) ) /v
    
                t = (rs + rr)/v             # resulting time
                it = np.floor(t/dt)         # nearest neighbor for timesample

                #print rs, rr, ix, iz, t, it
    
                if (it <= nsamples):

                    R[ix,iz] = R[ix,iz] + data[ioff,itrc,it] * wco /np.sqrt(2*np.pi)
    
    return R