calculate mod using pow function python

python pow
mark T picture mark T · Sep 23, 2015 · Viewed 22.9k times · Source

So, If i would like to calculate the value of 6^8 mod 5 using the pow function, what should I put in a line??

In the assumption that You don't need to import it first

I know that pow is used like pow (x, y) = pow (6, 8) = 6^8 and

My guess is 

mod.pow(6,8)

Thank you!

Answer

PM 2Ring picture PM 2Ring · Sep 23, 2015

It's simple: pow takes an optional 3rd argument for the modulus.

From the docs:

pow(x, y[, z])

Return x to the power y; if z is present, return x to the power y, modulo z (computed more efficiently than pow(x, y) % z). The two-argument form pow(x, y) is equivalent to using the power operator: x**y.

So you want:

pow(6, 8, 5)

Not only is pow(x, y, z) faster & more efficient than (x ** y) % z it can easily handle large values of y without using arbitrary precision arithmetic, assuming z is a simple machine integer.

Related questions

Exponentials in python: x**y vs math.pow(x, y)

Which one is more efficient using math.pow or the ** operator? When should I use one over the other? So far I know that x**y can return an int or a float if you use a decimal the function …

Read More
negative pow in python

I have this problem >>> import math >>> math.pow(-1.07,1.3) Traceback (most recent call last): File "<stdin>", line 1, in <module> ValueError: math domain error any suggestion ?

Read More
How do I list all files of a directory?

How can I list all files of a directory in Python and add them to a list?

Read More