Doxygen Source Code Documentation
eis_rst.c File Reference
#include "f2c.h"Go to the source code of this file.
Functions | |
| int | rst_ (integer *nm, integer *n, doublereal *w, doublereal *e, integer *matz, doublereal *z__, integer *ierr) |
Function Documentation
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Definition at line 8 of file eis_rst.c. References imtql1_(), and imtql2_().
00010 {
00011 /* System generated locals */
00012 integer z_dim1, z_offset, i__1, i__2;
00013
00014 /* Local variables */
00015 static integer i__, j;
00016 extern /* Subroutine */ int imtql1_(integer *, doublereal *, doublereal *,
00017 integer *), imtql2_(integer *, integer *, doublereal *,
00018 doublereal *, doublereal *, integer *);
00019
00020
00021
00022 /* THIS SUBROUTINE CALLS THE RECOMMENDED SEQUENCE OF */
00023 /* SUBROUTINES FROM THE EIGENSYSTEM SUBROUTINE PACKAGE (EISPACK) */
00024 /* TO FIND THE EIGENVALUES AND EIGENVECTORS (IF DESIRED) */
00025 /* OF A REAL SYMMETRIC TRIDIAGONAL MATRIX. */
00026
00027 /* ON INPUT */
00028
00029 /* NM MUST BE SET TO THE ROW DIMENSION OF THE TWO-DIMENSIONAL */
00030 /* ARRAY PARAMETERS AS DECLARED IN THE CALLING PROGRAM */
00031 /* DIMENSION STATEMENT. */
00032
00033 /* N IS THE ORDER OF THE MATRIX. */
00034
00035 /* W CONTAINS THE DIAGONAL ELEMENTS OF THE REAL */
00036 /* SYMMETRIC TRIDIAGONAL MATRIX. */
00037
00038 /* E CONTAINS THE SUBDIAGONAL ELEMENTS OF THE MATRIX IN */
00039 /* ITS LAST N-1 POSITIONS. E(1) IS ARBITRARY. */
00040
00041 /* MATZ IS AN INTEGER VARIABLE SET EQUAL TO ZERO IF */
00042 /* ONLY EIGENVALUES ARE DESIRED. OTHERWISE IT IS SET TO */
00043 /* ANY NON-ZERO INTEGER FOR BOTH EIGENVALUES AND EIGENVECTORS. */
00044
00045 /* ON OUTPUT */
00046
00047 /* W CONTAINS THE EIGENVALUES IN ASCENDING ORDER. */
00048
00049 /* Z CONTAINS THE EIGENVECTORS IF MATZ IS NOT ZERO. */
00050
00051 /* IERR IS AN INTEGER OUTPUT VARIABLE SET EQUAL TO AN ERROR */
00052 /* COMPLETION CODE DESCRIBED IN THE DOCUMENTATION FOR IMTQL1 */
00053 /* AND IMTQL2. THE NORMAL COMPLETION CODE IS ZERO. */
00054
00055 /* QUESTIONS AND COMMENTS SHOULD BE DIRECTED TO BURTON S. GARBOW, */
00056 /* MATHEMATICS AND COMPUTER SCIENCE DIV, ARGONNE NATIONAL LABORATORY
00057 */
00058
00059 /* THIS VERSION DATED AUGUST 1983. */
00060
00061 /* ------------------------------------------------------------------
00062 */
00063
00064 /* Parameter adjustments */
00065 z_dim1 = *nm;
00066 z_offset = z_dim1 + 1;
00067 z__ -= z_offset;
00068 --e;
00069 --w;
00070
00071 /* Function Body */
00072 if (*n <= *nm) {
00073 goto L10;
00074 }
00075 *ierr = *n * 10;
00076 goto L50;
00077
00078 L10:
00079 if (*matz != 0) {
00080 goto L20;
00081 }
00082 /* .......... FIND EIGENVALUES ONLY .......... */
00083 imtql1_(n, &w[1], &e[1], ierr);
00084 goto L50;
00085 /* .......... FIND BOTH EIGENVALUES AND EIGENVECTORS .......... */
00086 L20:
00087 i__1 = *n;
00088 for (i__ = 1; i__ <= i__1; ++i__) {
00089
00090 i__2 = *n;
00091 for (j = 1; j <= i__2; ++j) {
00092 z__[j + i__ * z_dim1] = 0.;
00093 /* L30: */
00094 }
00095
00096 z__[i__ + i__ * z_dim1] = 1.;
00097 /* L40: */
00098 }
00099
00100 imtql2_(nm, n, &w[1], &e[1], &z__[z_offset], ierr);
00101 L50:
00102 return 0;
00103 } /* rst_ */
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