Modules
Structs
Enums
Functions
Prepare
sigma[0] = rhop_u dot rhop_u => sigma_uu
sigma[1] = rhop_u dot rhop_d => sigma_ud
sigma[2] = rhop_d dot rhop_d => sigma_dd
Rayon parallel version to prepare
sigma[0] = rhop_u dot rhop_u => sigma_uu
sigma[1] = rhop_u dot rhop_d => sigma_ud
sigma[2] = rhop_d dot rhop_d => sigma_dd