[erlang-questions] [patch] new float_to_list/2
Serge Aleynikov
serge@REDACTED
Wed Jan 12 15:10:36 CET 2011
The reason I called it precision was to be consistent with the naming
convention of the printf function. Below is the extract from "man 3
printf", which refers to the digits after the decimal point as "precision":
f, F The double argument is rounded and converted to decimal
notation in the style [-]ddd.ddd, where the number of
digits after the decimal-point character is equal to the
precision specification. If the precision is missing,
it is taken as 6; if the precision is explicitly zero,
no decimal-point character appears. If a decimal point
appears, at least one digit appears before it.
I don't have a very strong preference for calling it precision or scale,
but I do have a strong preference for including this patch in the
distribution, because the default behavior of float_to_list/1 hard-coded
in C is deficient.
On 1/12/2011 4:58 AM, nox wrote:
> Il should be called "scale", shouldn't it?
>
> Le 12 janv. 2011 à 10:26, Pierpaolo Bernardi<olopierpa@REDACTED> a écrit :
>
>> On Wed, Jan 12, 2011 at 06:44, Serge Aleynikov<serge@REDACTED> wrote:
>>> Attached please find a patch that adds a new float_to_list/2 BIF. The patch
>>> was created off of the master branch of https://github.com/erlang/otp.
>>>
>>> This BIF solves a problem of float_to_list/1 that doesn't allow specifying
>>> the number of digits after the decimal point when formatting floats.
>>>
>>> float_to_list(Float, Options) -> string()
>>>
>>> Float = float()
>>> Options = [Option]
>>> Option = {precision, Precision::integer()} | compact
>>>
>>> Text representation of a float formatted using given options
>>>
>>> Returns a string which corresponds to the text
>>> representation of Float using fixed decimal point formatting.
>>> When precision option is specified
>>> the returned value will contain at most Precision number of
>>> digits past the decimal point. When compact option is provided
>>> the trailing zeros at the end of the list are truncated.
>>
>> I think the option is misnamed.
>>
>> In the usual terminology, 'precision' is the total number of
>> significative digits, not only the ones past the decimal point.
>>
>> Cheers
>> P.
>>
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