PRECISION (number)

  Class:  Inquiry function - Generic

  Returns the decimal precision in the model representing real
  numbers with the same kind type parameter as the argument.

  The "number" can be of real or complex type; it can be scalar or
  array valued.

  The result is a scalar of type default integer.  The result has the
  value INT((DIGITS("number") - 1) * LOG10(RADIX("number"))).  If
  RADIX("number") is an integral power of 10, 1 is added to the
  result.

  Example:

  If X is a REAL*4 value, PRECISION (X) has the value 6.  The value 6
  is derived from INT ((24-1) * LOG10 (2.)) = INT (6.92...).  For
  more information on the model for REAL*4, see the HP Fortran for
  OpenVMS Language Reference Manual.