# [IPython-user] ipython + visual

Ryan Krauss ryanlists at gmail.com
Mon Feb 27 18:24:33 CST 2006

Is there a way to use Ipython with the visual module (from Vpython)?
I need to run several demos using visual and there is a noticable lag
when it has to load scipy everytime (and I would just much prefer to
use Ipython than a regular python shell).

Below is a script that runs fine from the ipython prompt, but when I
close the visual window, Ipython exits.

Thanks,

Ryan

==================================
from visual import *

from scipy import arange,zeros_like, sin, cos, zeros, sqrt
from pylab import plot, figure, cla, show
from scipy.integrate import odeint
import time

tic=time.time

m=5.0
L=2.0
g=9.81

def invpend_rootlocus(s,K):
return 1.0/3.0*m*L**2*s**2-m*g*L/2.0+K

f1 = y2
f2 = 3*(tau-g*L*m*sin(y1)/2.0)/(L**2*m)
g11 = T*y2
g12 = 3*T*(tau-g*L*m*sin(y1)/2.0)/(L**2*m)
g21 = T*(y2+0.5*g12)
g22 = 3*T*(tau-g*L*m*sin(y1+0.5*g11)/2.0)/(L**2*m)
g31 = T*(y2+0.5*g22)
g32 = 3*T*(tau-g*L*m*sin(y1+0.5*g21)/2.0)/(L**2*m)
g41 = T*(y2+g32)
g42 = 3*T*(tau-g*L*m*sin(y1+g31)/2.0)/(L**2*m)
dy1 = (g41+2*g31+2*g21+g11)/6.0
dy2 = (g42+2*g32+2*g22+g12)/6.0
return dy1, dy2

scene.title = 'Pendulum'
scene.height = scene.width = 600

g = 9.8
L1 = 0.5 # physical length of upper assembly; distance between axles
d=0.1
gap=d

\section{Runge-Kutta Derivation}
\begin{maxima}
\parseopts{lhs='f1(y1,y2)'}
f1(y1,y2):=y2
\end{maxima}
\begin{maxima}
\parseopts{lhs='f2(y1,y2)'}
%    f2(y1,y2):=-4*(y1+y1^3)
f2(y1,y2):=(tau-m*g*L/2*sin(y1))*3/(m*L^2)
\end{maxima}
\begin{maxima}
\parseopts{lhs='g11'}
g11(y1,y2):=T*f1(y1,y2)
\end{maxima}
\begin{maxima}
\parseopts{lhs='g12'}
g12(y1,y2):=T*f2(y1,y2)
\end{maxima}
\begin{maxima}
\parseopts{lhs='g21'}
g21(y1,y2):=T*f1(y1+0.5*g11,y2+0.5*g12)
\end{maxima}
\begin{maxima}
\parseopts{lhs='g22'}
g22(y1,y2):=T*f2(y1+0.5*g11,y2+0.5*g12)
\end{maxima}
\begin{maxima}
\parseopts{lhs='g31'}
g31(y1,y2):=T*f1(y1+0.5*g21,y2+0.5*g22)
\end{maxima}
\begin{maxima}
\parseopts{lhs='g32'}
g32(y1,y2):=T*f2(y1+0.5*g21,y2+0.5*g22)
\end{maxima}
\begin{maxima}
\parseopts{lhs='g41'}
g41(y1,y2):=T*f1(y1+g31,y2+g32)
\end{maxima}
\begin{maxima}
\parseopts{lhs='g42'}
g42(y1,y2):=T*f2(y1+g31,y2+g32)
\end{maxima}
\begin{maxima}
\parseopts{lhs='dy1'}
dy1:1/6*(g11+2*g21+2*g31+g41);
\end{maxima}
\begin{maxima}
\parseopts{lhs='dy2'}
dy2:1/6*(g12+2*g22+2*g32+g42);
\end{maxima}
\begin{maxima-noout}
with_stdout ("test.f", [fortran(apply ("=", ['f1,
f1(y1,y2)])),fortran(apply ("=", ['f2, f2(y1,y2)])),fortran(apply
("=", ['g11, g11(y1,y2)])),fortran(apply ("=", ['g12,
g12(y1,y2)])),fortran(apply ("=", ['g21, g21(y1,y2)])),fortran(apply
("=", ['g22, g22(y1,y2)])),fortran(apply ("=", ['g31,
g31(y1,y2)])),fortran(apply ("=", ['g32, g32(y1,y2)])),fortran(apply
("=", ['g41, g41(y1,y2)])),fortran(apply ("=", ['g42,
g42(y1,y2)])),fortran(apply ("=", ['dy1, dy1])),fortran(apply ("=",
['dy2, dy2]))]);
\end{maxima-noout}
top = vector(0,0,0) # top of inner bar of U-shaped upper assembly
scene.center = top#-(0,L1/3,0)#-vector(0,(L1+L2)/2.,0)

axle = cylinder(pos=top, axis=(0,0,0.1), radius=d/4., color=color.yellow)

frame1 = frame(pos=top)
frame1.axis = (0,0,1)
theta=pi-0.1#0.5
frame1.rotate(axis=(0,0,1), angle=pi+theta)
bar1 = box(frame=frame1, pos=(0,L1/2,0),axis=(0,L1,0),
length=L1,width=d,height=d, color=color.red)

#pointer = arrow(pos=(1,0,0), axis=(0.2,0,0), shaftwidth=0.05)
#pointer2 = arrow(pos=(0,1,0), axis=(0,0.2,0), shaftwidth=0.05,color=color.red)
#pointer = arrow(frame=frame1,pos=(1,0,0), axis=(0.2,0,0),
shaftwidth=0.05, color=color.green)
#pointer2 = arrow(frame=frame1,pos=(0,1,0), axis=(0,0.2,0),
shaftwidth=0.05,color=color.blue)

scene.autoscale = 0

#dt = 0.001
#dt = 0.01
dt = 0.03
t = 0.
ts=20
tv=arange(0,ts+dt,dt)
thv=zeros_like(tv)
thdotv=zeros_like(tv)
x=0
#theta=pi-0.001#0.5

thv[0]=theta
#kp=100.0
#kd=30.0
kp=100
kd=0
while t<ts:
t1=tic()
rate(1./dt)
theta+=dy1
frame1.rotate(axis=(0,0,1), angle=dy1)
t += dt
x+= 1
thv[x]=theta