import scipy as sp
S0 = 9.15 ;T =1;n_steps=10;mu =0.15;sigma = 0.2
n_simulation =  10
dt =T/n_steps    
S = sp.zeros([n_steps], dtype=float)
x = range(0, int(n_steps), 1)
for j in range(0, n_simulation):
    S[0]= S0
for i in x[:-1]:
        e=sp.random.normal()
        S[i+1]=S[i,j]+S[i]*(mu-0.5*pow(sigma,2))*dt+sigma*S[i]*sp.sqrt(dt)*e;
    plot(x, S)
figtext(0.2,0.8,'S0='+str(S0)+',mu='+str(mu)+',sigma='+str(sigma))
figtext(0.2,0.76,'T='+str(T)+', steps='+str(int(n_steps)))
title('Stock price (number of simulations = %d ' % n_simulation +')')
xlabel('Total number of steps ='+str(n_steps)))
ylabel('stock price')
show()