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I have found many times a solution for my problems from here, but this time I am totally baffled. I don't know what's wrong at my code.

I made a code to create a box with charged particles inside with Vpython. As I launch the program, I get only a grey screen and the program crash. No error message, nothing.

from visual import *
from random import *

def electronizer(num):
    list = []
    electron_charge = -1.60217662e-19
    electron_mass = 9.10938356e-31
    for i in range(num):
        another_list = []
        e = sphere(pos=(random(), random(),random()), radius=2.818e-15, 
color=color.cyan)
        e.v = vector(random(), random(), random())
        another_list.append(e)
        another_list.append(e.v)
        another_list.append(electron_charge)
        another_list.append(electron_mass)
        list.append(another_list)
    return list

def protonizer(num):
    list = []
    proton_charge = 1.60217662e-19
    proton_mass = 1.6726219e-27
    for i in range(num):
        another_list = []
        p = sphere(pos=(random(), random(),random()), radius=0.8408739e-15, color=color.red)
        p.v = vector(random(), random(), random())
        another_list.append(p)
        another_list.append(p.v)
        another_list.append(proton_charge)
        another_list.append(proton_mass)
        list.append(another_list)
    return list

def cross(a, b):
    c = vector(a[1]*b[2] - a[2]*b[1],
         a[2]*b[0] - a[0]*b[2],
         a[0]*b[1] - a[1]*b[0])

    return c

def positioner(work_list):
    k = 8.9875517873681764e3 #Nm2/C2
    G = 6.674e-11 # Nm2/kg2
    vac_perm = 1.2566370614e-6 # H/m
    pi = 3.14159265
    dt = 0.1e-3
    constant = 1
    force = vector(0,0,0)
    for i in range(len(work_list)):
        for j in range(len(work_list)):
            if i != j:  
                r = work_list[i][0].pos - work_list[j][0].pos
                r_mag = mag(r)
                r_norm = norm(r)
                F = k * ((work_list[i][2] * work_list[j][2]) / (r_mag**2)) * r_norm
                force += F

                B = constant*(vac_perm / 4*pi) * (cross(work_list[j][2] * work_list[j][1], norm(r)))/r_mag**2
                F = cross(work_list[i][2] * work_list[i][1], B)
                force += F

                F = -(G * work_list[i][3] * work_list[j][3]) / r_mag**2 * r_norm
                force += F

        acceleration = force / work_list[i][3]
        difference_in_velocity = acceleration * dt
        work_list[i][1] += difference_in_velocity
        difference_in_position = work_list[i][1] * dt
        work_list[i][0].pos += difference_in_position

        if abs(work_list[i][0].pos[0]) > 2.5e-6:
            work_list[i][1][0] = -work_list[i][1][0]
        elif abs(work_list[i][0][1]) > 2.5e-6:
            work_list[i][1][1] = -work_list[i][1][1]
        elif abs(work_list[i][0][2]) > 2.5e-6:
            work_list[i][1][2] = -work_list[i][1][2]
return work_list

box = box(pos=(0, 0, 0), length = 5e-6, width = 5e-6, height = 5e-6, opacity = 0.5)

protons_num = raw_input("number of protons: ")
electrons_num = raw_input("number of electrons: ")
list_of_electrons = electronizer(int(electrons_num))
list_of_protons = protonizer(int(protons_num))
work_list = list_of_electrons + list_of_protons

while True:
    work_list = positioner(work_list)
A. Kristian Winstén
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1 Answers1

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You should ask your question on the VPython.org forum where the VPython experts hang out and will be able to answer your question. You should mention which operating system you are using and which version of python you are using. From your code I see that you are using classic VPython. There is a newer version of VPython 7 that just came out but the VPython syntax has changed.

John
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