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

Submitted by:  David E. Narvaez <dmaggot>
Submitted on:  Mon 22 Dec 2014 12:37:44 PM UTC  
 
Category: DocumentationSeverity: 3 - Normal
Operating System: Status: Wont Fix
Assigned to: NoneOpen/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>
Project 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>

 

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
  • -unavailable- added by psa (Updated the item)
  • -unavailable- added by dmaggot (Submitted the item)
  •  

    Please enter the title of George Orwell's famous dystopian book (it's a date):

     

     

    Follow 3 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Mon 29 Jun 2015 02:05:52 PM UTCpsaStatusNone=>Wont Fix
      Open/ClosedOpen=>Closed
    Mon 29 Jun 2015 02:04:42 PM UTCpsaAttached File-=>Added perm.c, #34342

    Back to the top


    Powered by Savane 3.1-cleanup1