[Maxima-bugs] [ maxima-Bugs-1064238 ] triangularize gives wrong results

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Bugs item #1064238, was opened at 2004-11-10 20:05
Message generated for change (Comment added) made by rtoy
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: triangularize gives wrong results

Initial Comment:
for example : 
(%i1) a:matrix([-4,0,-2],[0,1,0],[5,1,3]); 
								 [ - 4  0  - 
2 ] 
								 [	       ] 
(%o1) 								 [  0   
1   0  ] 
								 [	       ] 
								 [  5   1   
3  ] 
(%i2) determinant(a); 
(%o2) 								       
- 2 
(%i3) t:triangularize(a); 
								[ - 4   0   - 
2 ] 
								
[	        ] 
(%o3) 							        [  0   
- 4   0  ] 
								
[	        ] 
								[  0    0   - 
2 ] 
 
 
 
a and t doesn't even have the same determinant. 

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>Comment By: Raymond Toy (rtoy)
Date: 2004-11-19 16:56

Message:
Logged In: YES 
user_id=28849

I can obtain the desired matrix via elementary row operations.

Please cite a reference that says the determinant must match.

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Comment By: Nobody/Anonymous (nobody)
Date: 2004-11-19 15:18

Message:
Logged In: NO 

to rtoy 
 
"Why is this wrong?  The result is an upper triangular matrix." 
 
This is a joke ? 
You know [1 2 3],[0,5,6],[0,0,7] is too an upper triangular 
matrix. I thought the command triangularize(a) gives a 
triangular form of the matrix a an not an random upper 
triangular matrix. It seems you didn't read my comment "a and t 
doesn't even have the same determinant." . I hope you know 
that a matrix and a triangular form of this matrix should have 
the same determinant. 

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Comment By: Raymond Toy (rtoy)
Date: 2004-11-11 18:04

Message:
Logged In: YES 
user_id=28849

Why is this wrong?  The result is an upper triangular matrix.


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