real(kind(1.d0)) function zarg (z)

        implicit none
  c april 1977 version.  w. fullerton, c3, los alamos scientific lab.

        complex(kind(1.d0)) z

  
  c
        zarg = 0.0
        if (real(z).ne.0. .or. aimag(z).ne.0.) zarg =
       1  atan2 (aimag(z), real(z))
  c
        return
        end