Doxygen Source Code Documentation
eis_balbak.c File Reference
#include "f2c.h"Go to the source code of this file.
Functions | |
| int | balbak_ (integer *nm, integer *n, integer *low, integer *igh, doublereal *scale, integer *m, doublereal *z__) |
Function Documentation
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Definition at line 8 of file eis_balbak.c. References scale. Referenced by rg_().
00010 {
00011 /* System generated locals */
00012 integer z_dim1, z_offset, i__1, i__2;
00013
00014 /* Local variables */
00015 static integer i__, j, k;
00016 static doublereal s;
00017 static integer ii;
00018
00019
00020
00021 /* THIS SUBROUTINE IS A TRANSLATION OF THE ALGOL PROCEDURE BALBAK, */
00022 /* NUM. MATH. 13, 293-304(1969) BY PARLETT AND REINSCH. */
00023 /* HANDBOOK FOR AUTO. COMP., VOL.II-LINEAR ALGEBRA, 315-326(1971). */
00024
00025 /* THIS SUBROUTINE FORMS THE EIGENVECTORS OF A REAL GENERAL */
00026 /* MATRIX BY BACK TRANSFORMING THOSE OF THE CORRESPONDING */
00027 /* BALANCED MATRIX DETERMINED BY BALANC. */
00028
00029 /* ON INPUT */
00030
00031 /* NM MUST BE SET TO THE ROW DIMENSION OF TWO-DIMENSIONAL */
00032 /* ARRAY PARAMETERS AS DECLARED IN THE CALLING PROGRAM */
00033 /* DIMENSION STATEMENT. */
00034
00035 /* N IS THE ORDER OF THE MATRIX. */
00036
00037 /* LOW AND IGH ARE INTEGERS DETERMINED BY BALANC. */
00038
00039 /* SCALE CONTAINS INFORMATION DETERMINING THE PERMUTATIONS */
00040 /* AND SCALING FACTORS USED BY BALANC. */
00041
00042 /* M IS THE NUMBER OF COLUMNS OF Z TO BE BACK TRANSFORMED. */
00043
00044 /* Z CONTAINS THE REAL AND IMAGINARY PARTS OF THE EIGEN- */
00045 /* VECTORS TO BE BACK TRANSFORMED IN ITS FIRST M COLUMNS. */
00046
00047 /* ON OUTPUT */
00048
00049 /* Z CONTAINS THE REAL AND IMAGINARY PARTS OF THE */
00050 /* TRANSFORMED EIGENVECTORS IN ITS FIRST M COLUMNS. */
00051
00052 /* QUESTIONS AND COMMENTS SHOULD BE DIRECTED TO BURTON S. GARBOW, */
00053 /* MATHEMATICS AND COMPUTER SCIENCE DIV, ARGONNE NATIONAL LABORATORY
00054 */
00055
00056 /* THIS VERSION DATED AUGUST 1983. */
00057
00058 /* ------------------------------------------------------------------
00059 */
00060
00061 /* Parameter adjustments */
00062 --scale;
00063 z_dim1 = *nm;
00064 z_offset = z_dim1 + 1;
00065 z__ -= z_offset;
00066
00067 /* Function Body */
00068 if (*m == 0) {
00069 goto L200;
00070 }
00071 if (*igh == *low) {
00072 goto L120;
00073 }
00074
00075 i__1 = *igh;
00076 for (i__ = *low; i__ <= i__1; ++i__) {
00077 s = scale[i__];
00078 /* .......... LEFT HAND EIGENVECTORS ARE BACK TRANSFORMED */
00079 /* IF THE FOREGOING STATEMENT IS REPLACED BY */
00080 /* S=1.0D0/SCALE(I). .......... */
00081 i__2 = *m;
00082 for (j = 1; j <= i__2; ++j) {
00083 /* L100: */
00084 z__[i__ + j * z_dim1] *= s;
00085 }
00086
00087 /* L110: */
00088 }
00089 /* ......... FOR I=LOW-1 STEP -1 UNTIL 1, */
00090 /* IGH+1 STEP 1 UNTIL N DO -- .......... */
00091 L120:
00092 i__1 = *n;
00093 for (ii = 1; ii <= i__1; ++ii) {
00094 i__ = ii;
00095 if (i__ >= *low && i__ <= *igh) {
00096 goto L140;
00097 }
00098 if (i__ < *low) {
00099 i__ = *low - ii;
00100 }
00101 k = (integer) scale[i__];
00102 if (k == i__) {
00103 goto L140;
00104 }
00105
00106 i__2 = *m;
00107 for (j = 1; j <= i__2; ++j) {
00108 s = z__[i__ + j * z_dim1];
00109 z__[i__ + j * z_dim1] = z__[k + j * z_dim1];
00110 z__[k + j * z_dim1] = s;
00111 /* L130: */
00112 }
00113
00114 L140:
00115 ;
00116 }
00117
00118 L200:
00119 return 0;
00120 } /* balbak_ */
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