code 41539; real procedure LOGNORMAL(X, MU, SIGMA); value X, MU, SIGMA; real X, MU, SIGMA; LOGNORMAL:= if SIGMA ≤ 0 then STATAL3 ERROR(“LOGNORMAL”, 3, SIGMA) else if X ≤ 0 then 0 else PHI((LN(X) - MU) / SIGMA); eop