long double on ppc-darwin

[FX Coudert]

I'm trying to understand the gfortran failure large_real_kind_2.F90 on 
ppc-darwin7.9, which can be reduced to:

$ cat large_real_kind_2.F90
  real(kind=16) :: x
  real(8) :: y
  x = 1
  y = x
  x = cos (x)
  y = cos (y)
  print *, x, y, y-x

  end
$ ./usr/local/gfortran/bin/gfortran -g large_real_kind_2.F90 && ./a.out
  0.5403023058681397650104827000000        0.540302305868140       
1.9841535727186827560257490000000E-0004

But I can't make a C testcase for that. Is "long double" supposed to be 
usable on ppc-darwin7.9 ?

FX