returns the appropriate scale factor for the apriori coeff.
of the parameter indicated by index:
index .gt. 0 => index to prmter array (-30)
index .lt. 0 => -index div 100, -index mod 100 are
indices to a tesseral harmonic coefficient
index .eq.71 => site or spot radius or z comp
index .eq.72 => site or spot long or lat
index .gt. 80 => 1 of 6 factors for body ic's & params
entry SKALEINIT initializes scale factors for prmter array