TAN (real-number)

  Class:  Elemental function - Generic

  Returns the tangent of the argument.  The argument must be in
  radians; it is treated modulo 2*pi.

  +------+---------+----------+------------+-------------+
  | Args | Generic | Specific |  Argument  | Result Type |
  +------+---------+----------+------------+-------------+
  |  1   |  TAN    | TAN      | REAL*4     | REAL*4      |
  |      |         | DTAN     | REAL*8     | REAL*8      |
  |      |         | QTAN     | REAL*16    | REAL*16     |
  +------+---------+----------+------------+-------------+