complex(kind(1.d0)) function zcbrt (z)
      implicit none
c april 1977 version.  w. fullerton, c3, los alamos scientific lab.
      complex(kind(1.d0)) z
      real(kind(1.d0)) theta,zarg,r,dcbrt
      external zarg, dcbrt
c
      theta = zarg(z) / 3.0
      r = dcbrt (abs(z))
c
      zcbrt = cmplx (r*cos(theta), r*sin(theta), kind(1.d0))
c
      return
      end