doc: Use newer coding conventions in examples/code directory. * FIRfilter.m, FIRfilter_aggregation.m, display.m, subsasgn.m, subsref.m, display.m, end.m, get.m, numel.m, plot.m, polynomial.m, polynomial_superiorto.m, polyval.m, roots.m, set.m, subsasgn.m, subsref.m, celldemo.cc, fortrandemo.cc, funcdemo.cc, globaldemo.cc, oct_demo.cc, paramdemo.cc, stringdemo.cc: Use newer coding conventions in examples/code directory.

function out = subsasgn (f, index, val)

  switch (index.type)
    case "."
      fld = index.subs;
      if (! strcmp (fld, "polynomial"))
        error ('@FIRfilter/subsasgn: invalid property "%s"', fld);
      endif
      out = f;
      out.polynomial = val;

    otherwise
      error ("@FIRfilter/subsasgn: Invalid index type")
  endswitch

endfunction