Seawater density from salinity, temperature and pressure

From practical salinity, temperature and pressure values, the seawater density is computed.

This function computes the seawater density (kg/m3).
Inputs:
S = practical salinity (psu).
T = temperature (ºC).
p = pressure (bars).
Outputs:
rho = seawater density (kg/m3).
rhodif = seawater density difference (kg/m3).