#3.4 FE 3
var("N,P")
plot_vector_field((0.1*N*(1-(N/5000)),.001*N*P-.001*P),(N,-10,10),(P,-10,10),axes_labels=["Prey","Predator"])

#Practice Exam
def temp(t):
    if t>85:
        print "It's hot"
    elif t<65:
        print "It's cold"
    else:
        print "Not bad"
temp(86)
temp(64)
temp(75)

peng=[62,93,75,56,76]
ig=[34,21,15,25,34]
list_plot(zip(peng,ig),axes_labels=["Penguins","Iguanas"],color="green",size=30)

var("N","P")#Error 1, misplaced quotation marks. Creates symblic variables.
t = srange(0,100,0.1) #Error 2, missing parenthesis. Creates list from 0-100 in steps of .1 and assigns to t.
sol=desolve_odeint([0.5*N - 0.01*N*P, 0.5*0.01*N*P - 0.2*P],ics=[50,75], dvars=[N,P], times=t)#Error 3/4 Missing * between 0.2 and P with undefined variable t1. Runs euler's method on given equation.
list_plot((t, sol[:,0])) + list_plot(zip(t,sol[:,1]),#Error 6 second plot uses "plot", plots every value of N and P as they correspond to each other.
color="red")