函数名: sinh 
 功  能: 双曲正弦函数 
 用  法: #include <math.h> 
         double sinh(double x); 
 程序例: 
#include <stdio.h> 
 #include <math.h> 
int main(void) 
 { 
    double result, x = 0.5; 
   result = sinh(x); 
    printf("The hyperbolic sin() of %lf is %lf\n", x, result); 
    return 0; 
 }