# Re: [Jprogramming] Fractional parts

```All, Thanks for the help.

Here's some real numbers from a problem I'm working on:
Calculate some values from this equation:
v=:2%(3r19-%1 2 3 245 246 247 248)
v
_2.375 _5.84615 _11.4 13.0028 13.0014 13 12.9986
Raul's first suggestion:
1|v
0.625 0.153846 0.6 0.0027933 0.00139082 0 0.998621
More precision, but signs are wrong on the negative numbers.```
```
Nolaig's suggestion:
(- <.) v
0.625 0.153846 0.6 0.0027933 0.00139082 1.77636e_15 0.998621
Negative signs are still wrong, and the 6th entry should be zero. Looks
like a compare tolerance problem.

Pascal's solution:

1 (| |)v

0.375 0.846154 0.4 0.0027933 0.00139082 0 0.998621
Still has the negatives wrong.

Martin's solution:
fp=.**1||

fp v

_0.375 _0.846154 _0.4 0.0027933 0.00139082 0 0.998621
Negatives are right, zeroes are right. This fractional part verb needs to
be in the documentation as part of the numbers chapter.

Also the integer part verb: ip=.]-**1||    should be included in the
numbers section as well.
ip v

_2 _5 _11 13 13 13 12

Skip

Skip Cave
Cave Consulting LLC

On Sun, Aug 6, 2017 at 6:42 AM, Raul Miller <rauldmil...@gmail.com> wrote:

> 1&| does work, actually.
>
> And, if you want an offset of -1 on that result when the original
> value was negative, you can use (1&| - 0&>)
>
> Thanks,
>
> --
> Raul
>
> On Sun, Aug 6, 2017 at 3:19 AM, Martin Kreuzer <i...@airkreuzer.com>
> wrote:
> > In easy steps (and for further reference) ...
> >
> > From these test data (two floats, two integers, different signs), to get
> the
> > fractional parts
> >
> >    v=. 2.25 _8.11 16 _3
> >
> > simply taking the Residue (when dividing by 1) doesn't work (error at
> > negative float position)
> >
> >    1|v
> > 0.25 0.89 0 0
> >
> > So first get Magnitude
> >
> >    | v
> > 2.25 8.11 16 3
> >
> > then take Residue
> >
> >    1 | (| v)
> > 0.25 0.11 0 0
> >
> > then get the sign right (see Raul's remark below)
> >
> >    (*v) * (1 | | v)
> > 0.25 _0.11 0 0
> >
> > and put it as verb (fp), written as a fork
> >
> >    fp=. * * 1||
> >    fp v
> > 0.25 _0.11 0 0
> >
> > -M
> >
> >
> > At 2017-08-06 02:14, you wrote:
> >
> >> Eh... but that's wrong.  You can't add any integer to 0.542857 to get
> >> _0.542857.
> >>
> >> If you want signed fractions, you'd need something like (*@] * (| |))
> >>
> >> Thanks,
> >>
> >> --
> >> Raul
> >>
> >>
> >> On Sat, Aug 5, 2017 at 10:01 PM, 'Pascal Jasmin' via Programming
> >> <programm...@jsoftware.com> wrote:
> >> > combining other answers we get the cute:
> >>
> >> > 1 (| |)  _0.542857 _1.1875 1.96552 2.92308 4.13043 5.7 7.82353 10.8571
> >> > 15.5455 23.75
> >>
> >>
> >>
> >>
> >> > ________________________________
> >> > From: Bill <bbill....@gmail.com>
> >> > To: "programm...@jsoftware.com" <programm...@jsoftware.com>
> >> > Sent: Saturday, August 5, 2017 8:30 PM
> >> > Subject: Re: [Jprogramming] Fractional parts
> >>
> >>
> >>
> >> > this also depends on what do you expect for negative numbers.
> >>
> >> > Sent from my iPhone
> >>
> >> > On 6 Aug, 2017, at 7:35 AM, Skip Cave <s...@caveconsulting.com>
> wrote:
> >>
> >> >> Oops! i meant:
> >> >>
> >> >> How does one find the fractional parts of a vector of floating point
> >> >> numbers?
> >> >>
> >> >> 0.542857 1.1875 1.96552 2.92308 4.13043 5.7 7.82353 10.8571 15.5455
> >> >> 23.75
> >> >> 41.8 114 247
> >> >>
> >> >> i want:
> >> >> 0.542857 0.1875 0.96552 0.92308 0.13043 0.7 0.82353 0.8571 5.5455
> 0.75
> >> >> 0.8
> >> >> 0 0
> >> >>
> >> >> (Last two integers have zero fractional part.)
> >> >>
> >> >>
> >> >> Skip Cave
> >> >> Cave Consulting LLC
> >> >>
> >> >> On Sat, Aug 5, 2017 at 6:30 PM, Skip Cave <s...@caveconsulting.com>
> >> >> wrote:
> >> >>
> >> >>> How does one find the fractional parts of a vector of floating point
> >> >>> numbers?
> >> >>>
> >> >>> 0.542857 1.1875 1.96552 2.92308 4.13043 5.7 7.82353 10.8571 15.5455
> >> >>> 23.75
> >> >>> 41.8 114 247
> >> >>>
> >> >>> i want:
> >> >>> 0.542857 0.1875 0.96552 0.92308 0.13043 0.7 0.82353 0.8571 5.5455
> 0.75
> >> >>> 0.8
> >> >>> 114 247
> >> >>>
> >> >>> Skip
> >> >>>
> >> >>> Skip Cave
> >> >>> Cave Consulting LLC
> >> >> ------------------------------------------------------------
> ----------
> >> >> For information about J forums see http://www.jsoftware.com/
> forums.htm
> >>
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> forums.htm
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