zatanh.f 258 Bytes
complex(8) function zatanh (z)
      implicit none
c april 1977 version.  w. fullerton, c3, los alamos scientific lab.
      complex(8) z, ci, zatan
      external zatan
      data ci /(0.,1.)/
c
      zatanh = -ci*zatan(ci*z)
c
      return
      end