Where, as above, C is annuity payment, PV is principal, n is number of payments, starting at end of first period, and i is interest rate per period. Equivalently C is the periodic loan repayment for a loan of PV extending over n periods at interest rate, i.
Refractory epilepsy is a seizure disorder that resists drug treatment. There is some debate among clinicians and researchers about how to define refractory epilepsy. As a result, this term is used in a variety of ways, and when a patient's epilepsy is described as refractory, resistant, or nonresponsive, it can be advisable to ask for more detail about what the diagnosis means.
There's 4 parts of the Sexual Response. Erection (Parasympathetic), Emission (Sympathetic), Ejaculation (Somatic), and Resolution (Sympathetic). After resolution, there's the refractory period, which is generally controlled by the parasympathetic nervous system. The refractory period is what makes you tired. So along the point of your question, your assumption that orgasm is also a function of the PSNS is where you went wrong.