{c=N[1 - ( (1 - a/((h-20) (s - 11)))^ceil(h*v*3*10^-5) * (1 - b/((h-20) (v - 19 - s)))^ceil(h*v*1.5*10^-5))^(3 T)]} with h= 4200 ; v=1200 ; s = 350 ; a = 69 ; b = 69 ; T = 26