phc-discussions - Re: [PHC] A must read...

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Message-ID: <864181102.20140115182636@gmail.com>
Date: Wed, 15 Jan 2014 18:26:36 +0100
From: Krisztián Pintér <pinterkr@...il.com>
To: Solar Designer <solar@...nwall.com>
CC: discussions@...sword-hashing.net
Subject: Re: [PHC] A must read...

Solar Designer (at Wednesday, January 15, 2014, 3:54:15 PM):

> Besides integer multiply, I was considering floating-point

since it came up, i use this opportunity to ask the list:

how reliable floating point is from interop standpoint? i mean:

1, the in-memory storage of single and double types. can we expect
different architectures having same bit pattern for the same value?

2, exact results. should we expect different architectures supporting
the same type (like IEEE 754) to produce different results due to
different rounding or otherwise?

so at the end, my question for example is: if we take two 32 bit
words, treat them as singles, convert them to doubles, multiply them,
and then store the resulting double in a 64 bit word, can we expect
different architectures end up with different bit patterns?