VOID eispack_rs P9C(int, nm,
int, n,
double *, a,
double *, w,
int, matz,
double *, z,
double *, fv1,
double *, fv2,
int *, ierr)
{
/* this subroutine calls the recommended sequence of */
/* subroutines from the eigensystem subroutine package (eispack) */
/* to find the eigenvalues and eigenvectors (if desired) */
/* of a real symmetric matrix. */
/* on input */
/* nm must be set to the row dimension of the two-dimensional */
/* array parameters as declared in the calling program */
/* dimension statement. */
/* n is the order of the matrix a. */
/* a contains the real symmetric matrix. */
/* matz is an integer variable set equal to zero if */
/* only eigenvalues are desired. otherwise it is set to */
/* any non-zero integer for both eigenvalues and eigenvectors. */
/* on output */
/* w contains the eigenvalues in ascending order. */
/* z contains the eigenvectors if matz is not zero. */
/* ierr is an integer output variable set equal to an error */
/* completion code described in the documentation for tqlrat */
/* and tql2. the normal completion code is zero. */
/* fv1 and fv2 are temporary storage arrays. */
/* questions and comments should be directed to burton s. garbow, */
/* mathematics and computer science div, argonne national laboratory */
/* this version dated august 1983. */
/* ------------------------------------------------------------------ */
if (n <= nm) {
goto L10;
}
*ierr = n * 10;
goto L50;
L10:
if (matz != 0) {
goto L20;
}
/* .......... find eigenvalues only .......... */
tred1(nm, n, a, w, fv1, fv2);
/* tqlrat encounters catastrophic underflow on the Vax */
/* call tqlrat(n,w,fv2,ierr) */
tql1(n, w, fv1, ierr);
goto L50;
/* .......... find both eigenvalues and eigenvectors .......... */
L20:
tred2(nm, n, a, w, fv1, z);
tql2(nm, n, w, fv1, z, ierr);
L50:
return;
}
void EigenValues(const SymmetricMatrix& X, DiagonalMatrix& D,
SymmetricMatrix& A)
{ DiagonalMatrix E; tred3(X,D,E,A); tql1(D,E); }
