If we're just looking at a basic black-scholes model for a generic underlyer. We have:
C(S,t) = S*N(d1) - k*exp(-r*t)*N(d2)
P(S,t) = k*exp(-r*t)*N(-d2) - S*N(-d1)
d1 = (ln(s/k)+(r+si^2/2*)*t/(si*sqrt(t))
d2 = d1 - si*sqrt(t)
C(S,t): Price of a call
P(S,t): Price of a put
S...