-i sin ix = sinh x
cos ix = cosh x
tan ix = i tanh x
cot ix = -i coth x
sec ix = sech x
csc ix = -i csch x
双曲函数被如此命名大概是因参数曲线(sinh t, cosh t) 所描述的是一条
双曲线.
程序例:
#include <stdio.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;
}