CODEWITHSUNDEEP
rdivision
gaut
gaut

Reputation: 5958

in R, why does %% behave differently for decimal numbers?

in R, I want to check if a number is a multiple of another. this works well for integers

> 124%%1
[1] 0
> 124%%2
[1] 0

But for some mysterious reason doesn't work well with decimal numbers, any idea why 1.05%%0.05 is not 0?

> 0.05%%0.05
[1] 0
> 1.05%%0.05
[1] 0.05

Upvotes: 2

Views: 94

Answers (2)

IRTFM
IRTFM

Reputation: 263352

If you expected a 0 result then perhaps you would be satisfied with the results of multiplying both arguments by 100 (making these integer or at least close to them. )

(100*1.05)%%(100*0.05)
[1] 0

See @akrun's answer for "why".

Upvotes: 2

akrun
akrun

Reputation: 887193

According to ?"%%"

%% and x %/% y can be used for non-integer y, e.g. 1 %/% 0.2, but the results are subject to representation error and so may be platform-dependent. Because the IEC 60559 representation of 0.2 is a binary fraction slightly larger than 0.2, the answer to 1 %/% 0.2 should be 4 but most platforms give 5.

Upvotes: 6

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