unsupported operand type(s) for /: '_io.TextIOWrapper' and 'float'

Question

I'm getting an error message when trying to compile the following program. The goal is to analyze the behavior of a nonlinear pendulum and one particular Poincare section. I have attempted to print the data for the behavior of the pendulum to one file and the output corresponding to the Poincare section to another.

The error listed in the python shell reads as follows:

Traceback (most recent call last):
File "C:\Python32\Lib\site-packages\visual\examples\JMB312.py", line 39
    thetaDotDot = -(g / L) * sin(theta) - q * thetaDot + Fd * sin(Ohm * t)
TypeError: unsupported operand type(s) for /: '_io.TextIOWrapper' and 'float'

I really don't understand why io.TextIOWrapper is noted in this error or how to go about fixing the problem. Any help is appreciated!

CODE:

from visual import *
from visual.graph import *

scene.title = 'Pendulum'
scene.autoscale = False
scene.height = scene.width = 500
pivot = array([0,0,0])      # pivot position of pendulum
scene.center = pivot            # center scene on pendulum pivot
framesPerSecond = 400

myWindow1 = gdisplay(x=500, title = "Phase Space", xtitle="Theta", ytitle="ThetaDot", height=500, width=500)
f1 = gdots(gdisplay=myWindow1, color = color.cyan, size = 1)

myWindow2 = gdisplay(title="Poincare Section", xtitle="Theta", ytitle="ThetaDot",y=400, x=500, height=500, width=500)
f2 = gdots(gdisplay=myWindow2, color = color.yellow)

#initial conditions for pendulum 1
g = 9.8         # gravity
m = 1           # mass at end of rod
L = 9.8         # length of rod
theta = 0.2     # initial angle (from vertical)
thetaDot = 0    # start pendulum at rest
thetaDotDot = 0 # acceletation
dt = 0.04       # time step
t = 0           # time
Fd = 1.2        # drive force coefficient
Ohm = 2/3       # oscillatory coefficient for drive force
q = 0.5         # coefficient of friction

#pendulum 1 rod
rod = cylinder(pos=pivot, axis = (L*sin(theta),-L*cos(theta),0), radius = 0.1, color=color.cyan)

f=open('JMB312 data 1.txt','w')

g=open('JMB312 data 2.txt','w')

while t < 100000: #a lot of data
    thetaDotDot = -(g / L) * sin(theta) - q * thetaDot + Fd * sin(Ohm * t)
    thetaDot = thetaDot + thetaDotDot * dt
    theta = theta + thetaDot * dt

    time = str(t)
    angle = str(theta)
    angular_velocity = str(thetaDot)

    if t < 750:
        f.write(time)
        f.write(",")
        f.write(angle)
        f.write(",")
        f.write(angular_velocity)
        f.write("\n")

    f1.plot(pos=(theta,thetaDot))

    if -dt**2/4 < Fd * sin(Ohm * t) < dt**2/4: #print poincare section data to separate file        
        g.write(time)
        g.write(",")
        g.write(angle)
        g.write(",")
        g.write(angular_velocity)
        g.write("\n")

        f2.plot(pos=(theta,thetaDot)) 

    if theta > 2 * pi:
        theta = theta - 2 * pi
    if theta < -2 * pi:
        theta = theta + 2 * pi

    rod.axis = (L*sin(theta), -L*cos(theta), 0)

    t = t+dt    
g.close()
f.close()

Answer 1

Your are using g to store the gravity and to open a file, change the name in the g=open('JMB312 data 2.txt', 'w') line to some other value and it should work.