Unable to calculate the Determinant of a large matrix

AI Thread Summary
The discussion revolves around calculating the determinant of a specific large matrix with zeros on the diagonal and ones elsewhere. Participants suggest various methods, including recursion, combinatorial approaches, and row/column operations to simplify the matrix. A key point is the importance of understanding how certain row operations affect the determinant, particularly that multiplying a row changes the determinant while adding a multiple of one row to another does not. The conversation also touches on the geometric interpretation of determinants and the historical context of their definition. Ultimately, the Laplace expansion is highlighted as a powerful technique for finding determinants, especially in matrices with many zeros.
  • #51
I'm not sure what Hurkyl had in mind, but you can get the multiplicities by noting that Tr A = n. (I had this in my original post, but then edited it out so as not to be giving out too much info to the OP.)
 
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  • #52
Avodyne said:
I'm not sure what Hurkyl had in mind, but you can get the multiplicities by noting that Tr A = n. (I had this in my original post, but then edited it out so as not to be giving out too much info to the OP.)

Oh, yeah. That works. Thanks!
 
  • #53
Problem solved, it is time to http://arxiv.org/abs/math/9902004"
 
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  • #54
Why? This ones been solved at least two ways. I'm sure there's a million other ways. I'm still kind of leaning to the row reduction as the simplest.
 
  • #55
Dick said:
I can see how that will get you a minimal polynomial, but I don't see how to get to the characteristic polynomial. How do you count the multiplicities?
A is diagonalizable, and we know its rank.
 
  • #56
Count Iblis said:
Problem solved, it is time to http://arxiv.org/abs/math/9902004"

Well, there's one last point that I'm wondering about: where does this problem come from? Is it just a math question or does it relate to some actual physics or anything else?
 
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  • #57
Avodyne said:
I'm not sure what Hurkyl had in mind, but you can get the multiplicities by noting that Tr A = n. (I had this in my original post, but then edited it out so as not to be giving out too much info to the OP.)

What is the Tr A = n?
Do you mean transpose of A equals to n that is the size of the matrix?
 
  • #58
soopo said:
What is the Tr A = n?
Do you mean transpose of A equals to n that is the size of the matrix?

"Tr" means the "trace", i.e. the sum of all the diagonal elements. This is invariant under a change of basis:

Tr[A] = sum over i of A_{i,i}


Tr[S^(-1)AS] =(ommitting summation signs, we are summing over all epeated indices) =

S^(-1)_{i,k}A_{k,j}S_{j,i}= Tr[***^(-1)] = Tr[A]
 
  • #59
Count Iblis said:
"Tr" means the "trace", i.e. the sum of all the diagonal elements. This is invariant under a change of basis:

Tr[A] = sum over i of A_{i,i}


Tr[S^(-1)AS] =(ommitting summation signs, we are summing over all epeated indices) =

S^(-1)_{i,k}A_{k,j}S_{j,i}= Tr[***^(-1)] = Tr[A]

How can you solve the problem by using trace?
I cannot see how you can proceed with them.
 
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