# harmonica.filters.derivative_northing_kernel¶

harmonica.filters.derivative_northing_kernel(fft_grid, order=1)[source]

Filter for northing derivative in frequency domain

Return a xarray.DataArray with the values of the frequency domain filter for computing the northing derivative. The filter is built upon the frequency coordinates of the passed fft_grid and is defined as follows:

$g(\mathbf{k}) = (i k_n)^n$

where $$\mathbf{k}$$ is the wavenumber vector ($$\mathbf{k} = 2\pi \mathbf{f}$$ where $$\mathbf{f}$$ is the frequency vector), $$k_n$$ is the northing wavenumber component of $$\mathbf{k}$$, $$i$$ is the imaginary unit and $$n$$ is the order of the derivative.

Parameters
Returns

da_filter (xarray.DataArray) – Array with the kernel for the northing derivative filter in frequency domain.

References

[Blakely1995]