ref: 1c3422ef1d4b994ba5e156f6dba79df07dd88995
dir: /nan.h/
#pragma once
#if defined(__plan9__)
extern double D_PNAN, D_PINF;
#else
#define D_PNAN __builtin_nan("")
#define D_PINF __builtin_inf()
#endif
extern double D_NNAN, D_NINF;
void nan_init(void);