TRIRED
The
TRIRED
procedure uses
Householder's method to reduce a real, symmetric array to
tridiagonal form.
TRIRED is based on the routine
tred2
described in section 11.2 of
Numerical Recipes in C: The Art of Scientific Computing
(Second Edition), published by Cambridge University Press, and is used by permission.
Calling Sequence
TRIRED,
A, D, E
Arguments
A
An
n
by
n
real, symmetric array that is replaced, on exit, by the orthogonal array
Q
effecting the transformation. The routine TRIQL can use this result to find the eigenvectors of the array
A
.
D
An
n
-element output vector containing the diagonal elements of the tridiagonal array.
E
An
n
-element output vector containing the off-diagonal elements.
Keywords
DOUBLE
Set this keyword to force the computation to be done in double-precision arithmetic.
Example
See the description of
TRIQL
for an example using this function.
