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+--- Thread: How to plot a Graph (/thread-3293.html)
How to plot a Graph - Kamo - May-11-2017
Hello, I have an equation and need to plot a graph using the Euler method, the code looks like this:
h = 0.01
x = [0.0]
y = [0]
n = int(30/h)
def f(y,x):
eq = #something
return #something
for i in range (0,n):
xn = (i+1)*h
yn = y[i] + f(y[i],x[i])*h
x.append(xn)
y.append(yn)
#print (x[i],y[i])
plt.plot(x,y)
plt.xlabel("Time(t)")
plt.ylabel("Concentration(Cs)")
plt.title("Concentration by Time")
plt.show()But I have an equation, this one:10(105 + log(900)) -5*t = S^2 /2 +20S +20log(S)
So when t = 0, S = 30. So I need to plot the values of S as the time increase.
Any help how to solve the equation?? In fact, I need anything that use the euler method that allows me to plot the graph.
Thanks in advance!
RE: How to plot a Graph - Larz60+ - May-11-2017
See this example: https://matplotlib.org/users/pyplot_tutorial.html
RE: How to plot a Graph - zivoni - May-12-2017
It might help to say what do you mean with "plotting graph using euler method" - euler method usually means numerical method to solve first order ODE - and if you mean this method, then solving ODE and plotting result are two rather separate things.
Anyway your equation is not a differential equation, you can transform it to an explicit form as
t = f(S) and then straigtly plot it with matplotlib as Larz60+ suggested. And if you instist on using implicit equation, there is plot_implicit() function in sympy.plotting.