>>>>> "TH" == Ted Harding <ted.hard...@manchester.ac.uk>
>>>>> on Tue, 31 Mar 2009 13:59:41 +0100 (BST) writes:
TH> Hi Folks,
TH> Compare
TH> print(1234567890,digits=4)
TH> # [1] 1.235e+09
TH> print(1234567890,digits=5)
TH> # [1] 1234567890
TH> Granted that
TH> digits: a non-null value for 'digits' specifies the minimum
TH> number of significant digits to be printed in values.
TH> how does R decide to switch from the "1.235e+09" (rounded to
TH> 4 digits, i.e. the minumum, in "e" notation) to "1234567890" (the
TH> complete raw notation, 10 digits) when 'digits' goes from 4 to 5?
that's easy (well, as I'm one of the co-implementors ...) :
One of the design ideas has been to use "e"-notation only when
it's shorter (under the constraints given by 'digits'), i.e.,
1.2346e+09
is not shorter (but has less information) than
1234567890
hence the latter is chosen.
There are quite a few cases, and constraints (*) that apply
simultaneously, such that sometimes the default numeric
formatting may seem peculiar, but I hope that in the mean
time we have squished all real bugs here.
*) such as platform (in)dependency; S - back-compatibility, ..
Best regards,
Martin Maechler, ETH Zurich
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