CODEWITHSUNDEEP
pythonlogarithm
ArseniyRybasov
ArseniyRybasov

Reputation: 9

How to avoid inaccuracies in logarithms?

I will show you my problem with the help of this code:

from math import log
print(log(1000000, 10))

The result is:

5.999999999999999

I perfectly know that the problem occurs because computers use binary system and we use decimal.

I have already tried the Decimal library, but it didn't help me. This code:

from decimal import Decimal
print(log(Decimal("1000000"), Decimal("10")))

was giving me the same

5.999999999999999

How to fix this problem?

Edited: I forgot to mention that the base isn't necessarily 10!

Upvotes: 0

Views: 89

Answers (2)

lastchance
lastchance

Reputation: 6310

import sympy
print(sympy.log(1000000,10))

Outputs 6.

But, to be honest, it's better to be aware of the limitations of computers to store floating-point numbers to finite accuracy and not try to circumvent it.

Upvotes: 2

Sabil
Sabil

Reputation: 4510

You should try log10 as the following one

from math import log10

result = log10(1000000)
if result.is_integer():
    result = int(result)

print(result)

Upvotes: 0

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