[erlang-questions] display floats without -e?
Tue Jan 1 12:11:43 CET 2019
You might want to do some more testing.
It is not clear that this is something you would be happy with.
I discovered this by simplifying the code to
auto(F) when is_float(F) ->
P = precision(abs(F), 0),
-spec precision(float(), integer()) -> integer().
precision(A, P) ->
if A == trunc(A) -> P
; true -> precision(A*10.0, P+1)
and doing some testing of my own. I was rather relieved to discover
that the original code behaved the same way.
It's really not clear what the aim is here.
I suspect that it is something that should be
done with numbers rather than lists.
On Tue, 1 Jan 2019 at 23:43, PAILLEAU Eric <eric.pailleau@REDACTED> wrote:
> 1> c(floaty).
> 2> floaty:auto(12.345555).
> 3> floaty:auto(12.3455553333333).
> 4> list_to_float(floaty:auto(12.3455553333333)).
> Le 31/12/2018 à 20:31, Dan Sommers a écrit :
> > On 12/31/18 10:37 AM, Vans S wrote:
> > > > 1> 0.0001.
> > > 0.0001
> > > > 2> 0.00001.
> > > 1.0e-5
> > > Once floats get to the 4th/5th decimal place they start being
> > > displayed with the e-x notation. Is there a way to make them always
> > > display "normally", for example 0.00001 in this case ...
> > At some point, it's shorter and easier to read with the e-x notation.
> > Consider a number like 1e-44. The last thing I want is to have to count
> > all those zeros. ;-)
> > But you probably knew that.
> > > ... The problem is when you turn the float into a string, its also
> > > displayed as 1.0e-5, adding a format function works yes, but gets
> > > annoying to maintain when you need to do arithmetic on the floats.
> > > LIke sorting by the value.
> > I'm confused: if you're doing arithmetic on the floats, why are you
> > concerned with the strings?
> > If you're sorting the strings, then you'll probably either (a) have to
> > ensure a consistent format, perhaps with something like a ~24.18.0e
> > specifier, or (b) convert the strings back to floats and suffer various
> > rounding errors.
> > > Also debugging becomes annoying when you see the e-5, e-6, etc
> > > notation everywhere and have to match it up.
> > On that we agree. :-)
> > > Is there a way to compile / add arg to the VM to not do this?
> > I'm pretty new at Erlang, so I'm probably missing a lot, but how are you
> > displaying the values now if not with a format function? (I guess
> > there's io:write, but at that point, you're awfully close to calling
> > io:fwrite anyway.)
> > Are you just using the shell to do immediate calculations? I'm sure
> > that the shell has its own default formatting, or maybe it just calls
> > io:write.
> > Dan
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