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kedricz / back40computing

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Incorrect sorting on large arrays when doubles are all integral. #11

Open GoogleCodeExporter opened 8 years ago

GoogleCodeExporter commented 8 years ago 
What steps will reproduce the problem?
1. Perform a sort of sufficient size that LARGE_SORT is used.  Keys-only or 
keys with values will reproduce this issue.
2. Have the keys be doubles, but all of them be integers.
3. A basic example I use is the natural numbers decreasing from 1000000 to 1.

What is the expected output? What do you see instead?

I expect to see the numbers 1 through to 1000000 in increasing order.  I 
instead see negative numbers for the sorted keys.

What version of the product are you using? On what operating system?

Version v1.0.655 (SVN r655).  Windows 8 64-bit, targeting 64-bit, 
compute_13,sm_13.  Running on NVidia GEForce GTX 580.

Please provide any additional information below.

I have an (inelegant) workaround of multiplying all numbers by some number 
(7.76345621464357) before sorting, and dividing again afterwards, for problem 
sizes over 100,000.  This is of course not ideal - speed, roundoff, etc :).

Original issue reported on code.google.com by marksi...@gmail.com on 18 Feb 2013 at 9:00