_TRBAK3(3F)_TRBAK3(3F)NAME
TRBAK3, STRBAK3 - EISPACK routine. This subroutine forms the
eigenvectors of a REAL SYMMETRIC matrix by back transforming those of the
corresponding symmetric tridiagonal matrix determined by TRED3.
SYNOPSYS
subroutine trbak3(nm, n, nv, a, m, z)
integer nm, n, nv, m
double precision a(nv), z(nm,m)
subroutine strbak3(nm, n, nv, a, m, z)
integer nm, n, nv, m
real a(nv), z(nm,m)
DESCRIPTION
On Input
NM must be set to the row dimension of two-dimensional array parameters
as declared in the calling program dimension statement.
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 information about the orthogonal transformations used in the
reduction by TRED3 in its first N*(N+1)/2 positions.
M is the number of eigenvectors to be back transformed.
Z contains the eigenvectors to be back transformed in its first M
columns. On Output
Z contains the transformed eigenvectors in its first M columns. Note
that TRBAK3 preserves vector Euclidean norms. Questions and comments
should be directed to b. s. Garbow, APPLIED MATHEMATICS DIVISION, ARGONNE
NATIONAL LABORATORY
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