int write_nfloat32 (float const *f, int fd);
int read_nfloat64 (double *d, int fd);
int write_nfloat64 (double const *d, int fd);
int write_nfloat32 (float const *f, int fd);
int read_nfloat64 (double *d, int fd);
int write_nfloat64 (double const *d, int fd);