ValueError: operands could not be broadcast together with shapes (7,) (6,) (7,)

Question

I'm getting an error message trying to run a script in Python for repeated irradiation-cooling times of gold foil. This is the error:

Traceback (most recent call last):
  File "C:/Users/wolfk/PycharmProjects/Reactor Phys In-House/iterations.py", line 26, in <module>
    cr_tot /= math.e ** (-2.98256E-6 * out_times[l])
ValueError: operands could not be broadcast together with shapes (7,) (6,) (7,) 

The code is pretty messy since I used number values instead of variables for the most part, but the math isn't important, I can verify it later. What I need to do is get this thing to run! So you know, the vectors for in- and out-times are different lengths by design, and I tried making them the same length so that wasn't the issue. Here's the code:

import numpy as np
import math
import matplotlib.pyplot as plt

in_times = np.array([[697800, 603840, 74460, 161520, 428880, 75960, 62760]])
out_times = np.array([[248880, 3960, 9240, 5400, 5880, 8760]])

cr_tot = 0
cr_fast = 0
i = 1
j = 1
k = 0
l = 0

while i < 13:
    if j == 1:
        cr_tot /= math.e ** (-2.98256E-6 * in_times[k])
        cr_fast /= math.e ** (-2.98256E-6 * in_times[k])

        cr_tot += ((2.98256E-6 * 4950377) / 0.021554) / (1 - math.e ** (-2.98256E-6 * in_times[k]))
        cr_fast += ((2.98256E-6 * 2141114) / 0.043109) / (1 - math.e ** (-2.98256E-6 * in_times[k]))

        j -= 1
        k += 1
    else:
        cr_tot /= math.e ** (-2.98256E-6 * out_times[l])
        cr_fast /= math.e ** (-2.98256E-6 * out_times[l])

        j += 1
        l += 1

    i += 1

xi_tot = (2.98256E-6 * 4950377) / (0.021554 * cr_tot)
xi_fast = (2.98256E-6 * 2141114) / (0.043109 * cr_fast)

cr_tot *= (2.98256E-6 * 4950377) / (0.021554 * xi_tot * math.e ** (-2.98256E-6 * 660) * (1 - math.e ** (-2.98256E-6 * 1000)))
cr_fast *= (2.98256E-6 * 2141114) / (0.043109 * xi_fast * math.e ** (-2.98256E-6 * 660) * (1 - math.e ** (-2.98256E-6 * 2000)))

print(cr_tot)
print(cr_fast)

I'd appreciate any help I can get. :)

Answer 1

Removing the double brackets from your initial numpy arrays actually helps.

...
in_times = np.array([697800, 603840, 74460, 161520, 428880, 75960, 62760])
out_times = np.array([248880, 3960, 9240, 5400, 5880, 8760])
...

Output:

0.476018036910266
0.9882585377315589
0.9728174262826453
0.9840231812760558
0.9826154332766018
0.9742111371275044
7480153046556.081
175166298775.0072

Answer 2

I do not understand your logic. In your code, at beginning, k=0 and in_times[k]in if branch will return array([697800, 603840, 74460, 161520, 428880, 75960, 62760]). Thus, length of cr_tot is 7. And then j -= 1, j equals 0. Next iteration goes to else branch. out_times[l] means out_times[0] and it returns array([248880, 3960, 9240, 5400, 5880, 8760]) with length 6. But your code is cr_tot /= math.e ** (-2.98256E-6 * out_times[l]), dividing cr_tot(length is 6 return from if branch) using array with length 7. That is reason you got the error.