# round the floating point to nearest halfpoint

Discussion in 'Ruby' started by Lucky Nl, May 26, 2010.

1. ### Lucky NlGuest

Hi ,
I want to round the my floating point result into nearest halfpoint
how to do it.
Example:
1)My floating point result is 3.3
i want it become 3.5
2) My floating point result is 3.6
i want it become 4

How can we do it
--
Posted via http://www.ruby-forum.com/.

Lucky Nl, May 26, 2010

2. ### Robert KlemmeGuest

2010/5/26 Lucky Nl <>:
> =A0I want to round the my floating point result into nearest halfpoint
> .how to do it.
> =A0Example:
> =A0 1)My floating point result is 3.3
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0i want it become 3.5
> =A02) My floating point result is 3.6
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0i want it become 4

If you are rounding then 3.6 should yield 3.5 because (3.6 - 3.5) <<
(4 - 3.6). Otherwise you want the ceiling function.

> How can we do it

irb(main):012:0> [3.3, 3.6].map {|x| (x * 2).round / 2.0}
=3D> [3.5, 3.5]
irb(main):014:0> [3.3, 3.6].map {|x| (x * 2).ceil / 2.0}
=3D> [3.5, 4.0]

Btw, I would rather not round float values and use them as they are.
If at all I would usually only round them for output.

Cheers

robert

--=20
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

Robert Klemme, May 26, 2010

3. ### Benoit DalozeGuest

On 26 May 2010 15:09, Robert Klemme <> wrote:
>
> robert
>

.. was looking the exact names for rounding in BigDecimal.mode ..

Regards,
B.D.

Benoit Daloze, May 26, 2010