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