CODEWITHSUNDEEP
python
DaiWei
DaiWei

Reputation: 59

Double Asterisk

I'm new to Python and really stumped on this. I'm reading from a book and the code works fine; I just don't get it! 

T[i+1] = m*v[i+1]ˆ**/L

What's with the double asterisk part of this code? It's even followed by a forward slash. The variable L is initialized with the value 1.0 However, it looks like someone slumped over the keyboard, but the code works fine. Is this a math expression or something more? I would appreciate the help understanding this. Thanks!

full code:

from pylab import *
g = 9.8 # m/sˆ2
dt = 0.01 # s
time = 10.0 # s
v0 = 2.0 # s
D = 0.05 #
L = 1.0 # m
m = 0.5 # kg
# Numerical initialization
n = int(round(time/dt))
t = zeros(n,float)
s = zeros(n,float)
v = zeros(n,float)
T = zeros(n,float)
# Initial conditions
v[0] = v0
s[0] = 0.0
# Simulation loop
i = 0
while (i<n AND T[i]>=0.0):
    t[i+1] = t[i] + dt
    a = -D/m*v[i]*abs(v[i])-g*sin(s[i]/L)
    v[i+1] = v[i] + a*dt
    s[i+1] = s[i] + v[i+1]*dt
    T[i+1] = m*v[i+1]ˆ**/L + m*g*cos(s[i+1]/L)
    i = i + 1

Upvotes: 4

Views: 1953

Answers (2)

Frank V
Frank V

Reputation: 25419

What's with the double asterisk part of this code?

The answer to your core questions (at least as it exists of this writing) is the double asterisk (star) is power -- "raise to the power". So, i**3 would be "cube i".

My (cross check) source: https://stackoverflow.com/a/1044866/18196

Upvotes: 8

Delimitry
Delimitry

Reputation: 3027

This code is from the book "Elementary Mechanics Using Python: A Modern Course Combining Analytical and Numerical Techniques".
According to the formula on the page 255: enter image description here

So the Python line should be:

T[i+1] = m*v[i+1]**2/L + m*g*cos(s[i+1]/L)

Upvotes: 11

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