Why are there such inaccuracies in cosine and sinus?

Question

I do not know if anyone but me noticed that the cosinus and sinus function makes rounding errors. Is this problem only with Python? And how can you handle this?
https://code.sololearn.com/cmqG6prORUvu/?ref=app

Answer 1

Some people say that you should never check floating point types for equality with ==. Instead you can check if they are "almost" equal:

almost_equal = lambda m, n: abs(m-n)<=1e-6

print(cos(pi/4) == sin(pi/4))
# False

print(almost_equal(cos(pi/4), sin(pi/4)))
# True

Answer 2

Thanks, Anna, for your answer. I searched a bit on the internet. With round() there is also a suitable solution:
https://code.sololearn.com/cZIckb6D9gU1/?ref=app

Answer 3

Floating points numbers ain't 100% accurate.
You can check out this code

https://code.sololearn.com/cvKUsg91j1vQ/?ref=app

Answer 4

Anna You never said yourselves, just said some people.😀 Are you among them?

BTW, you've openly said you never understood the purpose of named lambdas before and you used them here…😂 (Just to type less here and different in actual code?)