Spectral coefficient of a derivative of a scalar function in the latitude direction

[Chayut Teeraratkul]

Hi,

I am trying to take the derivative of a scalar function in the latitude direction using this library. I understand that this task involves taking the inverse transform of the spectral coefficient of the function with the derivative of the associated Legendre polynomial. I cannot find any mention of this task under the scalar transforms in the documentation. I am wondering if there is a function in this library that can do this, and if so, how would one go about calling it in Fortran.

Thank you so much

[Nathanaël Schaeffer]

Hello,

The function you are looking for is SHsph_to_spat(), with a name that is admittedly not very descriptive.

From Fortran, it is the following:

    shtns_sph_to_spat(Spectral_array, Grad_lat_array, Grad_long_array)

where Spectral_array is the input spectral coefficients, while Grad_lat_array and Grad_long_array are filled by the function with the derivative in the spatial domain along the latitudinal and longitudinal directions respectively.

All the best

[Chayut Teeraratkul]

Thank you very much