y-derivative
for i = 1:nx for j = 1:ny
j2f[i,j] = 1.0im*wf[i,j]*ky[j]
j3f[i,j] = 1.0im*wf[i,j]*ky[j]/k2[i,j]
end~end
nxe = Int64(nx*1.5)
nye = Int64(ny*1.5)
j1f_p = zeros(ComplexF64,nxe,nye)
```

```
j2f_p = zeros(ComplexF64,nxe,nye)
j3f_p = zeros(ComplexF64,nxe,nye)
j4f_p = zeros(ComplexF64,nxe,nye)
qx = nxe-nx/2+1
qy = nye-ny/2+1