C++ namespace question

[Rik]

I need a little C++ help.  I'm deprecating is_NA in favor of isna within
the octave::math namespace.  The modified code in lo-mappers.h is

namespace octave
{
  namespace math
  {
    extern OCTAVE_API bool isna (double x);
    OCTAVE_DEPRECATED (4.4, "use 'octave::math::isna' instead")
    inline bool is_NA (double x) { return isna (x); }

    extern OCTAVE_API bool isna (float x);
    OCTAVE_DEPRECATED (4.4, "use 'octave::math::isna' instead")
    inline bool is_NA (float x) { return octave::math::isna (x); }

In one case, I wrote the inline substitute function without using the
namespace prefix, in the other I kept the prefix.  The code compiles fine,
but which is preferred?

--Rik