00010 {
00011     /* System generated locals */
00012     integer a_dim1, a_offset, z_dim1, z_offset;
00013 
00014     /* Local variables */
00015     extern /* Subroutine */ int figi_(integer *, integer *, doublereal *, 
00016             doublereal *, doublereal *, doublereal *, integer *), figi2_(
00017             integer *, integer *, doublereal *, doublereal *, doublereal *, 
00018             doublereal *, integer *), imtql1_(integer *, doublereal *, 
00019             doublereal *, integer *), imtql2_(integer *, integer *, 
00020             doublereal *, doublereal *, doublereal *, integer *);
00021 
00022 
00023 
00024 /*     THIS SUBROUTINE CALLS THE RECOMMENDED SEQUENCE OF */
00025 /*     SUBROUTINES FROM THE EIGENSYSTEM SUBROUTINE PACKAGE (EISPACK) */
00026 /*     TO FIND THE EIGENVALUES AND EIGENVECTORS (IF DESIRED) */
00027 /*     OF A SPECIAL REAL TRIDIAGONAL MATRIX. */
00028 
00029 /*     ON INPUT */
00030 
00031 /*        NM  MUST BE SET TO THE ROW DIMENSION OF THE TWO-DIMENSIONAL */
00032 /*        ARRAY PARAMETERS AS DECLARED IN THE CALLING PROGRAM */
00033 /*        DIMENSION STATEMENT. */
00034 
00035 /*        N  IS THE ORDER OF THE MATRIX  A. */
00036 
00037 /*        A  CONTAINS THE SPECIAL REAL TRIDIAGONAL MATRIX IN ITS */
00038 /*        FIRST THREE COLUMNS.  THE SUBDIAGONAL ELEMENTS ARE STORED */
00039 /*        IN THE LAST  N-1  POSITIONS OF THE FIRST COLUMN, THE */
00040 /*        DIAGONAL ELEMENTS IN THE SECOND COLUMN, AND THE SUPERDIAGONAL */
00041 /*        ELEMENTS IN THE FIRST  N-1  POSITIONS OF THE THIRD COLUMN. */
00042 /*        ELEMENTS  A(1,1)  AND  A(N,3)  ARE ARBITRARY. */
00043 
00044 /*        MATZ  IS AN INTEGER VARIABLE SET EQUAL TO ZERO IF */
00045 /*        ONLY EIGENVALUES ARE DESIRED.  OTHERWISE IT IS SET TO */
00046 /*        ANY NON-ZERO INTEGER FOR BOTH EIGENVALUES AND EIGENVECTORS. */
00047 
00048 /*     ON OUTPUT */
00049 
00050 /*        W  CONTAINS THE EIGENVALUES IN ASCENDING ORDER. */
00051 
00052 /*        Z  CONTAINS THE EIGENVECTORS IF MATZ IS NOT ZERO. */
00053 
00054 /*        IERR  IS AN INTEGER OUTPUT VARIABLE SET EQUAL TO AN ERROR */
00055 /*           COMPLETION CODE DESCRIBED IN THE DOCUMENTATION FOR IMTQL1 */
00056 /*           AND IMTQL2.  THE NORMAL COMPLETION CODE IS ZERO. */
00057 
00058 /*        FV1  IS A TEMPORARY STORAGE ARRAY. */
00059 
00060 /*     QUESTIONS AND COMMENTS SHOULD BE DIRECTED TO BURTON S. GARBOW, */
00061 /*     MATHEMATICS AND COMPUTER SCIENCE DIV, ARGONNE NATIONAL LABORATORY 
00062 */
00063 
00064 /*     THIS VERSION DATED AUGUST 1983. */
00065 
00066 /*     ------------------------------------------------------------------ 
00067 */
00068 
00069     /* Parameter adjustments */
00070     a_dim1 = *nm;
00071     a_offset = a_dim1 + 1;
00072     a -= a_offset;
00073     --fv1;
00074     z_dim1 = *nm;
00075     z_offset = z_dim1 + 1;
00076     z__ -= z_offset;
00077     --w;
00078 
00079     /* Function Body */
00080     if (*n <= *nm) {
00081         goto L10;
00082     }
00083     *ierr = *n * 10;
00084     goto L50;
00085 
00086 L10:
00087     if (*matz != 0) {
00088         goto L20;
00089     }
00090 /*     .......... FIND EIGENVALUES ONLY .......... */
00091     figi_(nm, n, &a[a_offset], &w[1], &fv1[1], &fv1[1], ierr);
00092     if (*ierr > 0) {
00093         goto L50;
00094     }
00095     imtql1_(n, &w[1], &fv1[1], ierr);
00096     goto L50;
00097 /*     .......... FIND BOTH EIGENVALUES AND EIGENVECTORS .......... */
00098 L20:
00099     figi2_(nm, n, &a[a_offset], &w[1], &fv1[1], &z__[z_offset], ierr);
00100     if (*ierr != 0) {
00101         goto L50;
00102     }
00103     imtql2_(nm, n, &w[1], &fv1[1], &z__[z_offset], ierr);
00104 L50:
00105     return 0;
00106 } /* rt_ */