#endif // Native SGI compilers
-#if defined ( sun )
+#if defined (__sun)
# include <strings.h>
# include <memory.h>
# if defined ( __cplusplus )
# define SG_GLU_H <OpenGL/glu.h>
# define SG_GLEXT_H <OpenGL/glext.h>
# define SG_GLUT_H <GLUT/glut.h>
+
+inline int (isnan)(double r) { return !(r <= 0 || r >= 0); }
#else
# define SG_GL_H <GL/gl.h>
# define SG_GLX_H <GL/glx.h>
#endif // SG_INCOMPLETE_FUNCTIONAL
#endif // _SG_COMPILER_H
+