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RE: AMD vs Intel

From: Bob Leary <bob.leary>
Date: Mon, 18 Nov 2019 17:21:30 +0000

I did a similar comparison man years ago (circa 2010) while chasing down a 1-bit difference in an Intel vs AMD floating point result. There is (or at least was) a slight difference in the 80 bit floating point hardware (Intel and AMD both use an 80 bit registers internal) and even found a reference somewhere in either an Intel or AMD document (sorry, no longer have it) that can give rise to this. Apparently there is a compiler switch that can be used to turn off
The internal 80-bit computation - see https://stackoverflow.com/questions/612507/what-are-the-applications-benefits-of-an-80-bit-extended-precision-data-type and answer therein that refer to this compiler option.

-----Original Message-----
From: owner-nmusers axnm.com <owner-nmusers@globomaxnm.com> On Behalf Of Leonid Gibiansky
Sent: Monday, November 18, 2019 12:05 PM
To: nmusers <nmusers@globomaxnm.com>
Subject: [NMusers] AMD vs Intel

Dear All,

I am testing the new Epyc processors from AMD (comparing with Intel Xeon), and getting different results. Just wondering whether anybody faced the problem of differences between AMD and Intel processors and knows how to solve it. I am using Intel compiler but ready to switch to gfortran or anything else if this would help to get identical results.
There were reports of Intel slowing the AMD execution in the past, but in my tests, speed is comparable but the results differ.

Thanks
Leonid


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buSp9xeMeKEbrUze
Received on Mon Nov 18 2019 - 12:21:30 EST

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