# Re: [Jprogramming] Fractional parts

```The purpose of the "negative fractional part" is to satisfy the identity
condition when the two parts are added back together:```
```
]v=:2%(3r19-%1 2 3 245 246 247 248)  NB. Create some long fractional
parts.

_2.375 _5.84615 _11.4 13.0028 13.0014 13 12.9986

fp=. * * 1||     NB. The fractional part verb

ip=: * * <.@|   NB. The integer part verb

]fpv =: fp v     NB. Save the fractional part

_0.375 _0.846154 _0.4 0.0027933 0.00139082 0 0.998621

]ipv =: ip v     NB. Save the integer part

_2 _5 _11 13 13 13 12

]sm =: ipv + fpv   NB. Add the two parts back together

_2.375 _5.84615 _11.4 13.0028 13.0014 13 12.9986

NB. The result of adding the two parts should be identical to the original
vector.

sm = v

1 1 1 1 1 1 1

Skip Cave
Cave Consulting LLC

On Tue, Aug 8, 2017 at 2:14 PM, 'Bo Jacoby' via Programming <
programm...@jsoftware.com> wrote:

> The integer part  a  and the fractional part  b  of a number  x  is such
> that x=a+b and  a  is an integer and   0<:b  and  b<1 . I do know of no use
> of a "negative fractional part".
>
>     Den 20:39 tirsdag den 8. august 2017 skrev Raul Miller <
> rauldmil...@gmail.com>:
>
>
>  I think we've mostly been using the wiki for live documents. (I'm not
> sure what all would be involved in changing the phrase book.)
>
> Thanks,
>
> --
> Raul
>
>
> On Tue, Aug 8, 2017 at 2:35 PM, Skip Cave <s...@caveconsulting.com> wrote:
> > It looks like we have a reliable solution to find a fractional part of a
> > floating point number, while maintaining the sign:
> >
> >    v
> >
> > _2.375 _5.84615 _11.4 13.0028 13.0014 13 12.9986
> >
> >    fp=. * * 1||    NB. Thanks to Martin
> >
> >    fp v
> >
> > _0.375 _0.846154 _0.4 0.0027933 0.00139082 0 0.998621
> >
> >
> > Credit should also go to the people who suggested the building blocks,
> e.g.
> >
> > (1|y) Raul  --  (1||y) Pascal  --  (*y) Raul
> >
> > It is also nice to have the companion verb - integer part:
> >
> >    ip=: * * <.@|      NB. Thanks to Louis
> >
> >    ip v
> >
> > _2 _5 _11 13 13 13 12
> >
> >
> > I have needed these functions more than once in my enginering work. I
> > believe that these two verbs need to be inserted somewhere in the
> "Numbers"
> > section of the J Phrases doc. Maybe under "8A-Numbers & Counting", or
> > 8C-Representations", or "8D-Arithmetic".
> >
> >
> > How do we get them in the document? What section do they fit the best in?
> > Can I edit the Phrases doc?
> >
> > Skip Cave
> > Cave Consulting LLC
> >
> >
> >
> >>
> >>
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