  Closed form expressions for a logarithm of general multivector (MV) in
base-free form in real geometric algebras (GAs) Cl(p,q) are presented for all
n=p+q=3. In contrast to logarithm of complex numbers (isomorphic to Cl(0,1), 3D
logarithmic functions, due to appearance of two double angle arc tangent
functions, allow to include two sets of sheets characterized by discrete
coefficients. Formulas for generic and special cases of individual blades and
their combinations are provided.
