double sin (double);
double cos (double);
double tan (double);

double asin (double); 结果介于[-PI/2, PI/2]
double acos (double); 结果介于[0, PI]
double atan (double); 反正切(主值), 结果介于[-PI/2, PI/2]
double atan2 (double, double); 反正切(整圆值), 结果介于[-PI/2, PI/2]

double sinh (double);
double cosh (double);
double tanh (double);

double exp (double);
double pow (double, double);
double sqrt (double);
double log (double); 以e为底的对数
double log10 (double);
log2 (double);//这个函数是有的

double ceil (double); 取上整
double floor (double); 取下整

double fabs (double);

double frexp (double f, int *p); 标准化浮点数, f = x * 2^p, 已知f求x, p ( x介于[0.5, 1] )
double ldexp (double x, int p); 与frexp相反, 已知x, p求f

double modf (double, double*); 将参数的整数部分通过指针回传, 返回小数部分
double fmod (double, double); 返回两参数相除的余数
source: 《C & C++ Code Capsules》

sqrt