Planck constant.
value = planck [value,sigma] = planck
planck returns the value of the Planck constant
in SI units (Joule*seconds)
in value and the standard
deviation in sigma (if two output arguments are specified).
The value and the standard deviation are taken from the 2002 CODATA collection of recommended values.
amu, avogadro, barn, bmagn, bohrrad, boltzm, clight, echarge, emass, faraday, gfree, hartree, molgas, nmagn, nmass, pmass, rydberg