MODULE = Myfunction     PACKAGE = Myfunction
PROTOTYPES: ENABLE

double do_nothing(x)
   AV * x
PREINIT:
   SV ** svnv;
   double x_db;
CODE:
   if(av_len(x) != 2) croak("bad array len");
   svnv = av_fetch(x, 0, 0);
   x_db = SvNV(*svnv);
   RETVAL = do_nothing(&x_db);
   sv_setnv_mg(*svnv, (NV)x_db);
OUTPUT:
   RETVAL