Convert a soil particle diameter dia [micro-meters] into
phi = -log2(dia). See also TT.phi2dia().
TT.dia2phi(dia)
Particle size diameter in micro-meters (will be converted in milli-meters)
Julien Moeys [aut, cre], Wei Shangguan [ctb], Rainer Petzold [ctb], Budiman Minasny [ctb], Bogdan Rosca [ctb], Nic Jelinski [ctb], Wiktor Zelazny [ctb], Rodolfo Marcondes Silva Souza [ctb], Jose Lucas Safanelli [ctb], Alexandre ten Caten [ctb]