Re: Double troubles

From:

"Oliver Wong" <owong@castortech.com>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 21 Mar 2007 10:45:19 -0400

Message-ID:

<BqcMh.51999$Zb.962917@weber.videotron.net>

"GeniousFayaz" <mohd.fayaz.r@gmail.com> wrote in message
news:1174038181.977159.8610@l75g2000hse.googlegroups.com...

I have 8 bytes and
I need to convert them to a single double.

[...]

but when I gave the following array
<code>
byte[] byteArray = new byte[]{0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
0x1};
</code>

instead of returning the value 1 (one) the above method returned me
some other
value. I even tried going through IEEE 754 standards but they were
absolutely
out of my scope.

http://www.psc.edu/general/software/packages/ieee/ieee.html explains IEEE
754 in as close to "plain English" as is reasonably possible for this
topic. In particular, they explain why the byte sequence
0x0000000000000001 does not equal the double value 1.0

There are many encoding systems for mapping from bytes to double and
back. You need to re-evaluated whether you want to use the IEEE 754
encoding specifically, or whether you want to use some special encoding
where 0x0000000000000001 maps onto 1.0. The two are mutually exclusive.

- Oliver.