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Thomas Hagedorn - Problem Typo

Thomas Hagedorn - Problem Typo

by Arnold Pizer -
Number of replies: 0
inactiveTopicProblem Typo topic started 9/9/2004; 6:11:32 PM
last post 9/13/2004; 1:00:10 PM
userThomas Hagedorn - Problem Typo  blueArrow
9/9/2004; 6:11:32 PM (reads: 1034, responses: 2)
We found a typo. In Problem


$j x_3 &

needs to be replaced by

$j x_5 &.

As currently written, a x_3 shows up in the x_5 column. It should really be an x_5.


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userArnold K. Pizer - Re: Problem Typo  blueArrow
9/10/2004; 1:44:56 PM (reads: 1295, responses: 0)
Thanks Tom,

The problem has been fixed and updated in the CVS.


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userThomas Hagedorn - Re: Problem Typo  blueArrow
9/13/2004; 1:00:10 PM (reads: 1292, responses: 0)

Unfortunately, there seems to be a worse bug in the system with that problem. Again, its problem


If you use seed 4856,

you'll get a problem with the variables chosen to be

a=4, b=-2, c=4, d=-2, e=-3, f=-2, g=5, i=2, j=8, k=-6, l=-1 (in the problem's code).

The solution should be

(-1,0,1,-2,0,0) + s(-4,1,0,0,0,0) + t(-8,0,-2,-2,1,0) + u(6,0,2,5,0,1)

If you enter that solution, you get credit. So far, so good.

The problem is that the problem also evaluates the answer

(-2,0,1,-2,0,0) + s(-4,1,0,0,0,0) + ... same as above

as correct. But it isn't correct. In fact, it appears to me that changing any of the the first vectors's entries not corresponding to the free variables x_2, x_5, x_6 results in a correct answer.

I looked at the code and it seems to me that the error must be occuring in the subroutine vec_solution_compare of the macro vec_solution_cmp. But I'm not proficient enought to have found the error.



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