LOG10 (real-number)

  Class:  Elemental function - Generic

  Returns the common log (base 10) of the argument.  The argument
  must be greater than zero.
  +------+---------+----------+------------+-------------+
  | Args | Generic | Specific |  Argument  | Result Type |
  +------+---------+----------+------------+-------------+
  |  1   |  LOG10  | ALOG10   | REAL*4     | REAL*4      |
  |      |         | DLOG10   | REAL*8     | REAL*8      |
  |      |         | QLOG10   | REAL*16    | REAL*16     |
  +------+---------+----------+------------+-------------+

  Note: The setting of compiler options specifying real
        size can affect ALOG10.