Re: Fractional part of decimal value.

2013/8/7 Jan Wielemaker <[email protected]>

> On 08/07/2013 05:15 PM, Carlo Capelli wrote:
>
>> Hi Wouter
>>
>>
>> when I had to compute numbers with fixed precisions (for instance,
>> presenting prices after taxes or discounts) I resorted to 'hardcode' the
>> precision in this way (here 2 decimal digits - actually � cents)
>>
>> ...
>> TwoDec is round(NoIva * 100) / 100,
>> ...
>>
>> or, using lambda:
>>
>> ...
>> FmtNum = \I^O^(T is round(I * 100) / 100, atom_number(A, T),
>> replace_word('.',',',A,O)),
>> ...
>>     call(FmtNum, DeltaG, DeltaF),
>>     call(FmtNum, Rate, RateF),
>>     call(FmtNum, Ivato, IvatoF),
>>     call(FmtNum, Cost, CostF),
>>
>
> Is this any different from this (assuming you do the . --> , for
> locale purposes)?
>
>
Of course, no.


> LC_NUMERIC=nl_NL.UTF-8 swipl-win
> 1 ?- format(atom(X), '~2:f', 1/3).
> X = '0,33'.
>
> (note the swipl-win :-)
>
>
From where it come ? :)


>         Cheers --- Jan
>
>
>
>
>  ...
>>
>> HTH
>>
>>
>>
>> 2013/8/7 Wouter Beek <[email protected]>
>>
>>  Hi all,
>>>
>>> I want to extract the integer and fractional part of a decimal value:
>>> ~~~{.pl}
>>> decimal_parts(D, I, F):-
>>>    I is floor(D / 1),
>>>    F is D - I * 1.
>>> ~~~
>>> What I get is the fractional part of the float value 1.1:
>>> ~~~
>>> ?- decimal_parts(1.1, _, F).
>>> F = 0.10000000000000009.
>>> ~~~
>>> I do not mind the padding zero's (just a notational difference), but I do
>>> not need the 9 at the end.
>>>
>>> Is there a way to get the same result as with e.g. C's modf (sample code
>>> below)? Thanks for any suggestions!
>>>
>>> ---
>>> Cheers,
>>> Wouter.
>>>
>>> Sample code in C:
>>> ~~~{.c}
>>> #include <stdio.h>
>>> #include <math.h>
>>>
>>> int main() {
>>>    double param, fractional_part, integer_part;
>>>    param = 1.1;
>>>    fractional_part = modf(param, &integer_part);
>>>    printf("%f = %f + %f \n", param, integer_part, fractional_part);
>>>    return 0;
>>> }
>>> ~~~
>>>
>>> Compile and run:
>>> ~~~
>>> $ gcc -Wall test.c -o test
>>> $ ./test
>>> 1.100000 = 1.000000 + 0.100000
>>> ~~~
>>>
>>> E-mail: [email protected]
>>> WWW: www.wouterbeek.com
>>> Tel.: 0647674624
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