Decimal in for python

Question

I have to evaluate a function (3x-2) in a interval [-10,10] with precision increments from 1, 0.1, 0.01, 0.001, 0.0001, etc. I tried this

a=1.0
for x in range(1,40):
    for y in range(-10,10,a):
        c=3(x)-2
        print(c)
    a=a/10

(The first for is because I need to get 40 decimals) But I got this error

for x in range(-10,10,a):
TypeError: 'float' object cannot be interpreted as an integer

Thanks for the help.

rahlf23 · Answer 1 · 2018-08-10T21:02:51.283

0

It looks like you are overthinking the problem. Here is a much simpler approach using numpy and matplotlib to visualize the answer:

import numpy as np
import matplotlib.pyplot as plt

desired_increment = 0.1
upper_bound = 10
lower_bound = -10
pts = int((upper_bound - lower_bound)/desired_increment + 1)

x = np.linspace(lower_bound, upper_bound, pts)

y = 3*x-2

plt.figure(1)
plt.plot(x,y,'*')
plt.show()

You can use np.linspace() to change the size of the increments that you mention.

edited Aug 10 '18 at 21:02

answered Aug 10 '18 at 20:28

rahlf23

8,869
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It worked, thanks. But I have a problem, I can't reach more that 8 or 10 decimals with this, do you know another way to reach to 40? and the intervals are in 2 instead of 1 – Rembrandt Sánchez Dosal Aug 10 '18 at 20:50
I don't know what you mean by 40 decimals. See my edit for achieving your desired increment. – rahlf23 Aug 10 '18 at 21:02
I need to increment by 1, then by 0.1, then by 0.01, then by 0.001, and so on until 0.0000000000000000000000000000000000000001 but with np.linspace() I can't reach more than 0.000000001 Do you know another alternative to reach this? – Rembrandt Sánchez Dosal Aug 10 '18 at 21:16
Why on Earth would you need 40th decimal precision.... – rahlf23 Aug 10 '18 at 21:20
I need to calculate the time that takes in every decimal precision and graph it (Homework stuff haha) – Rembrandt Sánchez Dosal Aug 10 '18 at 21:25
@RembrandtSánchezDosal how did you increment by `1, 0.1, 0.01` ? – Alan Kavanagh Mar 26 '19 at 11:27

Decimal in for python

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