Dear R Helpers, I am trying to extract the modulus from divisions by a sequence of fractions. I noticed that %% seems to behave inconsistently (to my untutored eye), thus:
> 0.1%%0.1 [1] 0 > 0.2%%0.1 [1] 0 > 0.3%%0.1 [1] 0.1 > 0.4%%0.1 [1] 0 > 0.5%%0.1 [1] 0.1 > 0.6%%0.1 [1] 0.1 > 0.7%%0.1 [1] 0.1 > 0.8%%0.1 [1] 0 > 0.9%%0.1 The modulus for 0.1, 0.2, 0.4 and 0.8 is zero, as I'd expect. But, the modulus for 0.3, 0.6, 0.7 and 0.9 is 0.1 - which I did not expect. I can see no obvious rule that predicts whether x%%0.1 will give an answer of 0 or 0.1. I could find no explanation of the way that %% works in the R manuals. So, I have 3 questions:- 1) Why is the modulus of 0.3%%0.1 (and 0.5%%0.1 and 0.6%%0.1...) not zero? 2) Are there any algorithms in R that use the %% operator with fractional divisors in this way, and do they know about its apparently inconsistent behaviour? 3) If %% is not intended for use with fractional divisors, then would it be a good idea to trap attempts to use them? Thanks, in advance, for your help Jonathan Williams ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
