VMS Help FORTRAN, Intrinsic Procedures, SQRT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  SQRT (number)

  A function that returns the square root of the argument.  The
  result is the principal value, with the real part greater than or
  equal to zero.  If the real part is zero, the result is the
  principal value, with the imaginary part greater than or equal to
  zero.
  +------+---------+----------+------------+-------------+
  | Args | Generic | Specific |  Argument  | Result Type |
  +------+---------+----------+------------+-------------+
  |  1   |  SQRT   | SQRT     | REAL*4     | REAL*4      |
  |      |         | DSQRT    | REAL*8     | REAL*8      |
  |      |         | QSQRT    | REAL*16    | REAL*16     |
  |      |         | CSQRT    | COMPLEX*8  | COMPLEX*8   |
  |      |         | CDSQRT   | COMPLEX*16 | COMPLEX*8   |
  |      |         | ZSQRT    | COMPLEX*16 | COMPLEX*8   |
  +------+---------+----------+------------+-------------+
  The argument for SQRT and DSQRT must be greater than or equal to
  zero.  The argument for QSQRT must be greater than zero.