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[luga] DEC Alpha problem (wie beim Pentium)

Date: Wed, 02 Jul 1997 15:14:24 -0400
From: "Gregory F. March" <march@BondNet.COM>
Subject: DEC Alpha Bug?!?

So there I am, looking at our trading system and noticing that the price of
one particular bond was different on two separate machines.  Damn, I think.
Must be a bug in the latest release of our software.  Quick, do a sum on all
the libraries.  Nope, they are the same.  Executable?  Nope, the same.
Hmm...  Step through the code, hey, look at that!  The pow() function is
returning different results!

So, I wrote a stand alone program.  Sure enough, the machine with the
latest rev motherboard (one that was just replaced by DEC) is
producing bad numbers.  Time to try 'dxcalc', DEX's X calculator.
Yup. different numbers.  How about perl?  Yup, different numbers.  How
about 'bc'?  Duh, bc doesn't take floating point powers.  Hmm... check
libm.  Nope, they are the same.

Bottom line:  DEC will be here shortly.

Test your alpha.  Try 'pow(1.234567, 7.654321)'.  If you don't get
5.017something, you have the same problem.

Risks?  In our case, could have been a large sum of money.

* Gregory F. March * http://www.gfm.net * march@gfm.net *

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