I now have another question. In looking at this there seem to be some
fundamental floating point problems that arise between base 10 number
entry and base 2 computer representation. Namely that 1.8, (say as an
example number, I might not be remembering right that this was an
actual example number given,) might be a reasonably nice and exactly
precise number in base 10 but it does not have a nice and exactly
precise conversion to base 2 which results in you ending up with an
inexact and imprecise base 2 representation.
Sure, but likewise there are obvious a.b values in base 2 which have no
equivalent in base 10.
OK, I am currently looking at some 'c' to java exact, to the best of
my abilities, ports of some log code. So, I have a double I now want
to return as probably a BigDecimal. Do I return more precise values by
going double -> Double -> String -> BigDecimal or is the precision
possibly already doomed and I might just as well just go double ->
BigDecimal?
if it's already a double, then it's already base-2 "imprecise", and
susceptible as such. Converting it to a String buys you nothing,
though you might do new BigDecimal("1.8");
An easy but inefficient way to get a numerical (non-string) value of
the form a.b into BigDecimal precisely is to say: new
BigDecimal(ab).movePointLeft(1)
For example, new BigDecimal(18).movePointLeft(1) is 1.8 exactly.
Sean
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