symb = symbolic(obj)
symb = symbolic(obj) returns
true if symbolic calculation mode is on,
false for numeric mode.
symbolic(obj, symb) sets whether the calculations are in
false) mode. Switching to symbolic mode, the
spin values, matrix elements, magnetic field, magnetic structure and
physical units are converted into symbolic variables. If this is not
desired, start with a symbolic mode from the beggining and have full
control over the values of the above mentioned variables.