I started programming two weeks ago, so I realize this might be a stupid question. I want to find the y values for the t values in the interval [0,25], without using a for loop. I want a list of y values, but instead I get <function y at 0x01D4D5D0>
:
from math import cos, e, sqrt
import numpy as np
m = 9
A = 0.3
k = 4
gamma = 0.15
t_array = np.linspace(0,25)
y_array = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
def y(t_array):
y = []
y.append(A*(e**(-gamma)**(t_array))*cos((sqrt(k/m))*(t_array)))
print(y)
Your original problem arises due to the fact that you don't call the function you define. You cannot expect a function to know what arguments it must work with. Python is procedural; you must pass those arguments yourself.
Alternatively (and I recommend this), you could just use numpy
's ufuncs and vectorise everything:
y_array = A * (np.exp(-gamma) ** (t_array)) * np.cos((np.sqrt(k / m)) * (t_array))
print(y_array)
array([ 0.3 , 0.26197643, 0.20012117, 0.12471753, 0.04610095,
-0.02650152, -0.08584334, -0.12718585, -0.14847109, -0.1501709 ,
-0.13487525, -0.10670268, -0.07062388, -0.03178614, 0.00508595,
0.03615761, 0.05878548, 0.07164338, 0.07468336, 0.06895966,
0.05635461, 0.03925115, 0.0201959 , 0.00159182, -0.01454951,
-0.02677677, -0.03428127, -0.03689604, -0.0350233 , -0.02950888,
-0.02148485, -0.01220259, -0.00287629, 0.0054473 , 0.01198185,
0.0162522 , 0.01810327, 0.0176719 , 0.01533013, 0.01161037,
0.00712318, 0.00247811, -0.00178419, -0.00524252, -0.00762514,
-0.00881889, -0.00885931, -0.00790559, -0.00620522, -0.00405386]
Disclaimer : I cannot verify this answer because you have not explained what you are trying to do. This should hopefully get you started in the right direction working with vectorisation.
i think the problem is that you have a function called 'y' and printing y prints the function location. Also the function y is not ran only defined and it does not return anything as well. So to print the newly created y list inside the y function you can do:
def y(t_array):
y_values = []
y_values.append(A*(e**(-gamma)**(t_array))*cos((sqrt(k/m))*(t_array)))
return y_values
print(y(t_array))
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