r - Strange numeric behaviour with paste function -

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can explain strange decimal behavior reproduced below? , how avoid it? use rounding suppose, don't see should need to.

x <- 200.10  y <- 200.96 paste("difference", x - y, sep = ":") # [1] "difference:-0.860000000000014" # not here! 200.10-200.96 # -0.86

there nothing strange going on. precision in both case same printed differently.

sprintf("difference: %.2f", x - y)  # prints -0.86 in last output  options(digits=15);  200.10-200.96  # prints -0.860000000000014 in first output

the precision in both case determined type (which double in case). see https://stat.ethz.ch/r-manual/r-devel/library/base/html/double.html , https://stat.ethz.ch/r-manual/r-devel/library/base/html/zmachine.html


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