interpolate
#define interpolate(x, x1, y1, x2, y2, n) \
#undef interpolate
#define interpolate(x, x1, y1, x2, y2, n) \
#undef interpolate
#undef interpolate
#define interpolate(parm, old, new) ((parm##_old * (old) + \
interpolate(char ms[], FILE *fp, char *fn, int f)