RuntimeWarning: invalid value encountered in divide

Question

I have to make a program using Euler\'s method for the \"ball in a spring\" model

from pylab import*
from math import*
m=0.1
Lo=1
tt=30
k=200
t=20
g=9.81
dt=0.01         


        

Answer 1

To prevent division by zero you could pre-initialize the output 'out' where the div0 error happens, eg np.where does not cut it since the complete line is evaluated regardless of condition.

example with pre-initialization:

a = np.arange(10).reshape(2,5)
a[1,3] = 0
print(a)    #[[0 1 2 3 4], [5 6 7 0 9]]
a[0]/a[1]   # errors at 3/0
out = np.ones( (5) )  #preinit
np.divide(a[0],a[1], out=out, where=a[1]!=0) #only divide nonzeros else 1