Added graph.py (no convergence neither)

graph.py

+# -*- coding: utf-8 -*-
+
+
+def RRK4(function, t_0, f_0, t_f, dt):
+    import matplotlib.pyplot as mpl
+    T = [t_0]
+    F = [f_0]
+    while T[-1] < t_f:
+        try:
+            t = T[-1]
+            x = F[-1]
+            K_1 = function(t,x)
+            K_2 = function(t + (dt/2), [x_i + (dt/2)*k_i for x_i,k_i in zip(x,K_1)])
+            K_3 = function(t + (dt/2), [x_i + (dt/2)*k_i for x_i,k_i in zip(x,K_2)])
+            K_4 = function(t + dt, [x_i + dt*k_i for x_i,k_i in zip(x,K_3)])
+            T.append(t + dt)
+            F.append([x_i + (dt/6)*(k1 + 2*k2 + 2*k3 + k4) for k1,k2,k3,k4,x_i in zip(K_1,K_2,K_3,K_4,x)])
+        except OverflowError:
+            break
+    sol = [T,[f[0] for f in F],[f[3] for f in F]]
+    mpl.plot(sol[0],sol[1], label = "f(η)")
+    mpl.plot(sol[0],sol[2], label = "θ(η)")
+    mpl.legend()
+    mpl.show()
+
+
+Pr = 7
+f_2_0 = 0.01
+th_1_0 = 0.00001
+        
+
+def couche_lim(eta, f):
+    return (f[1],f[2],-3*f[0]*f[2] + 2*(f[1]**2) - f[3], f[4],-3*Pr*f[0]*f[4])
+    
+
+
+if __name__ == "__main__":
+    print("Couche limite de vitesses")
+    RRK4(couche_lim, 0, [0,0,f_2_0,1,th_1_0], 2.4, 0.001)
+