[R] Problem with <= (less than or equal): not giving the expected result

[Rainer Johannes]

Dear All,

I have the following problem:

I have a function in which I check if the difference between values is smaller or equal to a certain threshold. I however realized that I might get there some unexpected results:

> abs(1 - 0.95) >= 0.05
[1] TRUE
## So that’s fine, but:
> abs(1 - 0.95) <= 0.05
[1] FALSE

Apparently, abs(1 - 0.95) is not equal to 0.05, which I find however quite disturbing.

Along these lines:
> abs(0.95 - 1) > 0.05
[1] TRUE
> abs(0.95 - 1) < 0.05
[1] FALSE

I guess that has to do with the floating point representation of the data?

Is there something I miss or is there any solution to this?
Thanks for any help!

cheers, jo



I tried this on different R-version (including 3.2.3 and 3.3.0 alpha); The R-version I used for the code above is:

> sessionInfo()
R version 3.0.2 (2013-09-25)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base