bugPSPP - Bugs: bug #25099, Floating Origin Needed

 
 

bug #25099: Floating Origin Needed

Submitted by:  John Darrington <jmd>
Submitted on:  Mon 15 Dec 2008 10:59:48 AM UTC  
 
Category: Graphical User InterfaceSeverity: 5 - Average
Status: FixedAssigned to: None
Open/Closed: ClosedRelease: None
Effort: 0.00

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Tue 10 Mar 2009 07:27:53 AM UTC, comment #4:

Oops! How embarrasing! There were some places where I'd used float instead of double.

Thanks for opening my eyes Ben. I should have done the numerical analysis before diagnosing the problem.

I've pushed a fix and closing this item.

John Darrington <jmd>
Project Administrator
Tue 10 Mar 2009 06:26:16 AM UTC, comment #3:

Presumably this occurs due to the inaccuracy of large integers when represented as doubles. But a 64-bit IEEE double can represent any integer up to 9,007,199,254,740,992 (2*53) without loss of precision, which is much larger than 107 < 2*24. Where are our 29 binary orders of magnitude going?

Ben Pfaff <blp>
Project Administrator
Tue 10 Mar 2009 05:57:33 AM UTC, comment #2:

Screenshot of what it looks like attached.

(file #17637)

Ben Pfaff <blp>
Project Administrator
Tue 10 Mar 2009 05:54:10 AM UTC, comment #1:

I had to use more than 1,000,000 cases to see this effect. Here is a program that generates an appropriate data file:

Ben Pfaff <blp>
Project Administrator
Mon 15 Dec 2008 10:59:48 AM UTC, original submission:

When viewing a dataset with very large numbers of cases
( > 500,000) the cell boundaries become unstable.

This is the classic "floating origin" problem. Its cause and solution is described at http://floatingorigin.com

John Darrington <jmd>
Project Administrator

 

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Attached Files
file #17637:  foo.png added by blp (35KiB - image/png)

 

Depends on the following items: None found

Items that depend on this one: None found

 

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  • -unavailable- added by blp (Posted a comment)
  • -unavailable- added by jmd (Submitted the item)
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    Follow 3 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Tue 10 Mar 2009 07:27:53 AM UTCjmdStatusNone=>Fixed
      Open/ClosedOpen=>Closed
    Tue 10 Mar 2009 05:57:33 AM UTCblpAttached File-=>Added foo.png, #17637

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