python - Euler function not giving results -

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we have programmed euler function study population changes.

he used while loop keep our values in biological range (no births, etc.). when run script, plot axis range -0.6 +0.6 , no graph drawn.

does know wrong code?

t=np.zeros((n+1))  in range (n):      t[i+1]=t[i]+dt  s = np.zeros((n+1)) z = np.zeros((n+1)) r = np.zeros((n+1)) s[0] = n-1 z[0] =1 i=0   while s[i]>0 , s[i] <n , z[i] < n , z[i] > 0 , r[i] >0 , r[i] <n , i<n:      s[i+1] = s[i]+dt*(-b*s[i]*z[i])     z[i+1] = z[i]+dt*(b*s[i]*z[i]-a*z[i])     r[i+1] = r[i]+dt*(a*z[i])     i=i+1  self.trace(t,s,r,z,i)  def trace(self,t, s, r, z, i):         plt.plot(t[:i],s[:i],'b')        plt.plot(t[:i],z[:i],'r')        plt.plot(t[:i],r[:i],'y')        plt.show()

i see r initialized as:

r = np.zeros((n+1))

then in while loop conditions require r[i] >0.

since i=0, r[i]=0 , condition false loop not execute.

perhaps missing initialization of r[0] = ...


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