[R] precision in seq

[jim holtman]

FAQ 7.31

On 2/4/08, Eric Elguero <Eric.Elguero at mpl.ird.fr> wrote:
> Hi everybody,
>
> this is a warning more than a question.
>
> I noticed that seq produces approximate results:
>
> > seq(0,1,0.05)[19]==0.9
> [1] TRUE
> > seq(0,1,0.05)[20]==0.95
> [1] FALSE
> > seq(0,1,0.05)[21]==1
> [1] TRUE
>
> > seq(0,1,0.05)[20]-0.95
> [1] 1.110223024625157e-16
>
> I do not understand why 0.9 and 1 are correct (within some
> tolerance or strictly exact?)  and 0.95 is not.
>
> this one works:
>
> > ((0:20)/20)[20]==0.95
> [1] TRUE
>
> Eric Elguero
>
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> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

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