Diagonalizing a matrix for special matrix

In MATLAB can I find a specific package to diagonal my matrix, I have somehow an specific matrix in which all elements of diagonal are zer0 and there is nonzero( ver small numbers) numbers just when j=i+1 or j=i-1. can I diagonal this matrix in a better way than just writing eig(A)?

[Matt J]

I don't think this structure alone let's you do efficient diagonalization. If it were possible, I think the info would be here

http://en.wikipedia.org/wiki/Tridiagonal_matrix

Is there any other structure - symmetric, Toeplitz, circulant, etc...?

[mim]

yes the matrix is symmetric and all none zero elements are positive