[Rd] Precision of function mean,bug?

[Morgan Morgan]

Hello R-dev,

Yesterday, while I was testing the newly implemented function pmean in
package kit, I noticed a mismatch in the output of the below R expressions.

set.seed(123)
n=1e3L
idx=5
x=rnorm(n)
y=rnorm(n)
z=rnorm(n)
a=(x[idx]+y[idx]+z[idx])/3
b=mean(c(x[idx],y[idx],z[idx]))
a==b
# [1] FALSE

For idx= 1, 2, 3, 4 the last line is equal to TRUE. For 5, 6 and many
others the difference is small but still.
Is that expected or is it a bug?

Thank you
Best Regards
Morgan Jacob

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