Generally, if it pays c dollars for every period, the present value is c/r.

推广开来,如果在每段时期内支付c美元,那么它的现值就是c/r

耶鲁公开课 - 金融市场课程节选

If you had a perpetuity, which paid C/2 forever, you already know from the perpetuity formula that the value of that would be C/2 divided by r/2 if r/2 is the discount rate.

如果你有一只永续债券,每半年付息C/2,没有到期日,从永续债券的公式可以知道,债券价格等于C/2除以r/2,r/2为贴现率

耶鲁公开课 - 金融市场课程节选