TRED2 Procedure

Reduces a real, symmetric matrix to tridiagonal form, using Householder's method.

TRED2, a [, d [, e]]

a An n-by-n real, symmetric matrix.

a This input parameter is replaced, on output, by the orthogonal matrix Q, effecting the transformation. The TQLI procedure uses this result to find the eigenvectors of the matrix A.

d (optional) An n-element vector containing the diagonal elements of the tridiagonal matrix.

e (optional) An n-element vector containing the off-diagonal elements of the tridiagonal matrix.

None.

TQLI

TRED2 is based on a routine of the same name in Numerical Recipes in C: The Art of Scientific Computing, by Flannery, Press, Teukolsky, and Vetterling, Cambridge University Press, Cambridge, MA, 1988. It is used by permission.