dsh_basis

paleokalmag.utils.dsh_basis(lmax, z, R=6371.2)[source]

Evaluate the magnetic field basis functions (derivatives of spherical harmonics).

Parameters:

  • lmax (int) – The maximum spherical harmonics degree

  • z (array) –

    The points at which to evaluate the basis functions, given as

    • z[0, :] contains the colatitude in degrees.

    • z[1, :] contains the longitude in degrees.

    • z[2, :] contains the radius in kilometers.

    Any additional columns are ignored.

  • R (float, optional) – The reference radius in kilometers. Default is REARTH=6371.2 km.

Returns:

An array of shape (lmax*(lmax+2), 3*z.shape[1]), containing the basis functions.

Return type:

array