_TRED3(3F)_TRED3(3F)NAME
TRED3, STRED3 - EISPACK routine. This subroutine reduces a REAL
SYMMETRIC matrix, stored as a one-dimensional array, to a symmetric
tridiagonal matrix using orthogonal similarity transformations.
SYNOPSYS
subroutine tred3(n, nv, a, d, e, e2)
integer n, nv
double precision a(nv), d(n), e(n), e2(n)
subroutine stred3(n, nv, a, d, e, e2)
integer n, nv
real a(nv), d(n), e(n), e2(n)DESCRIPTION
On Input n is the order of the matrix.
NV must be set to the dimension of the array parameter A as declared in
the calling program dimension statement.
A contains the lower triangle of the real symmetric input matrix, stored
row-wise as a one-dimensional array, in its first N*(N+1)/2 positions.
On Output
A contains information about the orthogonal transformations used in the
reduction.
D contains the diagonal elements of the tridiagonal matrix.
E contains the subdiagonal elements of the tridiagonal matrix in its last
N-1 positions. E(1) is set to zero.
E2 contains the squares of the corresponding elements of E. E2 may
coincide with E if the squares are not needed. Questions and comments
should be directed to B. S. Garbow, APPLIED MATHEMATICS DIVISION, ARGONNE
NATIONAL LABORATORY
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