Hi I am trying to create a visual for a physics problem using ivisual. The best visual I could find to describe the problem is below:
The problem I am having is I found an example in a text book of the same problem. The textbook visualizes the answers using visual module, however from the research I have been doing I believe that the visual module is now called ivisual. I can get the answer numerically when I hash out the function call and any other code that uses the ivisual module. In my specific example the masses are 10 and 20 and the length of each rope segment is 3, 4, and 4, and the distance between a and a is 8. I tried fixing the visual code, but I cannot get it work, it is probably something stupid.
My code is below with the error I am currently getting:
from ivisual import *
from numpy.linalg import solve
import numpy as np
import math as m
scene = display(x=0,y=0,width=500,height=500,
title='String and masses configuration')
tempe = curve(x=range(0,500),color=color.black)
n = 9
eps = 1*10**(-6)
deriv = np.zeros( (n, n), float)
f = np.zeros( (n), float)
x = np.array([0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 1., 1., 1.])
def plotconfig():
for obj in scene.objects:
obj.visible=0 # to erase the previous configuration
L1 = 3.0
L2 = 4.0
L3 = 4.0
xa = L1*x[3] # L1*cos(th1)
ya = L1*x[0] # L1 sin(th1)
xb = xa+L2*x[4] # L1*cos(th1)+L2*cos(th2)
yb = ya+L2*x[1] # L1*sin(th1)+L2*sen(th2)
xc = xb+L3*x[5] # L1*cos(th1)+L2*cos(th2)+L3*cos(th3)
yc = yb-L3*x[2] # L1*sin(th1)+L2*sen(th2)-L3*sin(th3)
mx = 100.0 # for linear coordinate transformation
bx = -500.0 # from 0=< x =<10
my = -100.0 # to -500 =<x_window=>500
by = 400.0 # same transformation for y
xap = mx*xa+bx # to keep aspect ratio
yap = my*ya+by
ball1 = sphere(pos=(xap,yap), color=color.cyan,radius=15)
xbp = mx*xb+bx
ybp = my*yb+by
ball2 = sphere(pos=(xbp,ybp), color=color.cyan,radius=25)
xcp = mx*xc+bx
ycp = my*yc+by
x0 = mx*0+bx
y0 = my*0+by
line1 = curve(pos=[(x0,y0),(xap,yap)], color=color.yellow,radius=4)
line2 = curve(pos=[(xap,yap),(xbp,ybp)], color=color.yellow,radius=4)
line3 = curve(pos=[(xbp,ybp),(xcp,ycp)], color=color.yellow,radius=4)
topline = curve(pos=[(x0,y0),(xcp,ycp)], color=color.red,radius=4)
def F(x, f): # Define F function
f[0] = 3*x[3] + 4*x[4] + 4*x[5] - 8.0
f[1] = 3*x[0] + 4*x[1] - 4*x[2]
f[2] = x[6]*x[0] - x[7]*x[1] - 10.0
f[3] = x[6]*x[3] - x[7]*x[4]
f[4] = x[7]*x[1] + x[8]*x[2] - 20.0
f[5] = x[7]*x[4] - x[8]*x[5]
f[6] = pow(x[0], 2) + pow(x[3], 2) - 1.0
f[7] = pow(x[1], 2) + pow(x[4], 2) - 1.0
f[8] = pow(x[2], 2) + pow(x[5], 2) - 1.0
def dFi_dXj(x, deriv, n): # Define derivative function
h = 1*10**(-4)
for j in range(0, n):
temp = x[j]
x[j] = x[j] + h/2.
F(x, f)
for i in range(0, n): deriv[i, j] = f[i]
x[j] = temp
for j in range(0, n):
temp = x[j]
x[j] = x[j] - h/2.
F(x, f)
for i in range(0, n): deriv[i, j] = (deriv[i, j] - f[i])/h
x[j] = temp
for it in range(1, 100):
rate(1) # 1 second between graphs
F(x, f)
dFi_dXj(x, deriv, n)
B = np.array([[-f[0]], [-f[1]], [-f[2]], [-f[3]], [-f[4]], [-f[5]],[-f[6]], [-f[7]], [-f[8]]])
sol = solve(deriv, B)
dx = np.take(sol, (0, ), 1) # take the first column of matrix sol
for i in range(0, n):
x[i] = x[i] + dx[i]
plotconfig()
errX = errF = errXi = 0.0
for i in range(0, n):
if ( x[i] != 0.): errXi = abs(dx[i]/x[i])
else: errXi = abs(dx[i])
if ( errXi > errX): errX = errXi
if ( abs(f[i]) > errF ): errF = abs(f[i])
if ( (errX <= eps) and (errF <= eps) ): break
print('Number of iterations = ', it)
print('Solution:')
for i in range(0, n):
print('x[', i, '] = ', x[i])
AttributeError Traceback (most recent call last)
<ipython-input-5-78050c1f23ab> in <module>()
76 for i in range(0, n):
77 x[i] = x[i] + dx[i]
---> 78 plotconfig()
79 errX = errF = errXi = 0.0
80
<ipython-input-5-78050c1f23ab> in plotconfig()
10
11 def plotconfig():
---> 12 for obj in scene.objects:
13 obj.visible=0 # to erase the previous configuration
14 L1 = 3.0
AttributeError: 'NoneType' object has no attribute 'objects'
