bugGNU Scientific Library - Bugs: bug #43868, gsl_permutation_mul is described...

 
 

You are not allowed to post comments on this tracker with your current authentication level.

bug #43868: gsl_permutation_mul is described backwards

Submitter:  David E. Narvaez <dmaggot>
Submitted:  Mon 22 Dec 2014 12:37:44 PM UTC
   
 
Category:  Documentation Severity:  3 - Normal
Operating System:  Status:  Wont Fix
Assigned to:  None Open/Closed:  Closed
Release:  1.15

Mon 29 Jun 2015 02:04:42 PM UTC, comment #1: 

The code and documentation are actually correct. Note that the permutation acts by exchanging columns instead of rows, so the nested index does the right thing. The attached code (perm.c) checks this on two simple permuations:

Pa = [0,1,3,2]
Pb = [1,3,2,0]

and makes sure gsl_permutation_mul gives the expected results. A quick check by hand shows that it does.

(file #34342)

Patrick Alken <psa>
Group administrator
Mon 22 Dec 2014 12:37:44 PM UTC, original submission:  

The documentation says it calculates p = pa pb, which is applying pb first, then pa; but the code does pb->data[pa->data[i]] which is p = pb pa.

David E. Narvaez <dmaggot>

 

(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attached Files
file #34342:  perm.c added by psa (2KiB - text/x-csrc)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -email is unavailable- added by psa (Updated the item)
  • -email is unavailable- added by dmaggot (Submitted the item)
  •  

    Follow 3 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2015-06-29 psa StatusNone Wont Fix
        Open/ClosedOpen Closed
    2015-06-29 psa Attached File- Added perm.c, #34342

    Back to the top

    Powered by Savane 3.13-3230.
    Corresponding source code