Hex to Float Conversion

[Bryan Joseph]

Hi, is there any way in Elixir to turn a hexadecimal into a float?

[José Valim]

Assuming hex is a binary you can do:

binary_to_integer("ABC", 16) * 1.0

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Lead Developer

On Thu, Mar 6, 2014 at 4:32 PM, Bryan Joseph <brya...@gmail.com> wrote:

Hi, is there any way in Elixir to turn a hexadecimal into a float?

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[Bryan Joseph]

Sorry I pressed the reply to author instead of reply to post.

It's a bit more complicated than that. I am creating a geospatial library for Elixir. One of the things I'm trying to do is convert to and from the Well Known Binary format which stores the numbers as floats.

For example: 4000000000000000 should equal 2.0

The example is from wikipedia:

http://en.wikipedia.org/wiki/Well-known_text

[Eric Meadows-Jönsson]

First convert the binary to its integer value, like José showed: value = binary_to_integer(binary, 16) then you can convert it to an IEEE754 float with << value :: [float, 64] >>. Change to 32 if it is in binary32 format instead of binary64.

--
Eric Meadows-Jönsson

[Bryan Joseph]

I'm still trying to get to the correct value. I have the following:

iex(86)> value = binary_to_integer("4000000000000000", 16)

4611686018427387904

iex(87)> new_value = << value :: [float, 64] >>

<<67, 208, 0, 0, 0, 0, 0, 0>>

How do I get from the bitstring to the float value (which in this case should be 2.0)?

[José Valim]

<< value :: [float, 64] >> = <<67, 208, 0, 0, 0, 0, 0, 0>>

It returns 4.611686018427388e18 though for that particular bitstring.

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Lead Developer

[Bryan Joseph]

I think this may be something I will have to try to implement myself. The good news is if I get it working I can contribute it back to the language!

Thanks guys. I'm really enjoying Elixir a lot. At this point it has become my language of choice whenever I'm doing something.

[Gilbert Kennen]

On 03/06/14 17:33, Bryan Joseph wrote:
> I think this may be something I will have to try to implement myself.
> The good news is if I get it working I can contribute it back to the
> language!
>
> Thanks guys. I'm really enjoying Elixir a lot. At this point it has
> become my language of choice whenever I'm doing something.
>

This seems to work.

<< value :: [float, 64] >> = << binary_to_integer("4000000000000000",
16) :: [integer, 64] >>

2.0 = value

It also seems to work with other values such as c000000000000000 and -2.0.

[Bryan Joseph]

It works! Thanks!