fcvt
bp = fcvt(dval,
char *fcvt();
extern char *fcvt(double, int, int *, int *);
extern char *fcvt(double, int, int *_RESTRICT_KYWD, int *_RESTRICT_KYWD);
bp = fcvt(dval, min(prec, MAXFCVT), &decpt, &sign);