extern double fabs(double), floor(double), ceil(double), modf(double, double *);
extern double sqrt(double), atof(char *);
extern double sin(double), cos(double), tan(double);
extern double asin(double), acos(double), atan(double), atan2(double, double);
extern double frexp(double, int *), ldexp(double, int);
extern double log(double), log10(double), pow(double, double), exp(double);
extern double sinh(double), cosh(double), tanh(double);