C ( S t , K , t , T , r ) = S t ⋅ N ( d 1 ) − e − r ( T − t ) ⋅ K ⋅ N ( d 2 ) C(S_t,K,t,T,r)=S_t\cdot N(d_1)-e^{-r(T-t)} \cdot K\cdot N(d_2) C(St,K,t,T,r)=St⋅N(d1)−e−r(T−t)⋅K⋅N(d2) N ( d ) = 1 2 π ∫ − ∞ d e − 1 / 2 x 2 d x N(d)=\frac{1}{\sqrt{2\pi}}\int_{-\infty}^{d}{e^{-1/2}x^2}dx N(d)=2π1∫−∞de−1/2x2dx d 1 = l o g ( s T / K ) + ( r + σ 2 / 2 ) ( T − t ) σ T − t d_1=\frac{log(s_T/K)+(r+\sigma^2/2)(T-t)}{\sigma\sqrt{T-t}} d1=σT−tlog(sT/K)+(r+σ2/2)(T−t) d 2 = l o g ( s T / K ) + ( r − σ 2 / 2 ) ( T − t ) σ T − t d_2=\frac{log(s_T/K)+(r-\sigma^2/2)(T-t)}{\sigma\sqrt{T-t}} d2=σT−tlo