Doxygen Source Code Documentation
eis_cbabk2.c File Reference
#include "f2c.h"Go to the source code of this file.
Functions | |
| int | cbabk2_ (integer *nm, integer *n, integer *low, integer *igh, doublereal *scale, integer *m, doublereal *zr, doublereal *zi) |
Function Documentation
|
||||||||||||||||||||||||||||||||||||
|
Definition at line 8 of file eis_cbabk2.c. References scale. Referenced by cg_().
00010 {
00011 /* System generated locals */
00012 integer zr_dim1, zr_offset, zi_dim1, zi_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 */
00022 /* CBABK2, WHICH IS A COMPLEX VERSION OF BALBAK, */
00023 /* NUM. MATH. 13, 293-304(1969) BY PARLETT AND REINSCH. */
00024 /* HANDBOOK FOR AUTO. COMP., VOL.II-LINEAR ALGEBRA, 315-326(1971). */
00025
00026 /* THIS SUBROUTINE FORMS THE EIGENVECTORS OF A COMPLEX GENERAL */
00027 /* MATRIX BY BACK TRANSFORMING THOSE OF THE CORRESPONDING */
00028 /* BALANCED MATRIX DETERMINED BY CBAL. */
00029
00030 /* ON INPUT */
00031
00032 /* NM MUST BE SET TO THE ROW DIMENSION OF TWO-DIMENSIONAL */
00033 /* ARRAY PARAMETERS AS DECLARED IN THE CALLING PROGRAM */
00034 /* DIMENSION STATEMENT. */
00035
00036 /* N IS THE ORDER OF THE MATRIX. */
00037
00038 /* LOW AND IGH ARE INTEGERS DETERMINED BY CBAL. */
00039
00040 /* SCALE CONTAINS INFORMATION DETERMINING THE PERMUTATIONS */
00041 /* AND SCALING FACTORS USED BY CBAL. */
00042
00043 /* M IS THE NUMBER OF EIGENVECTORS TO BE BACK TRANSFORMED. */
00044
00045 /* ZR AND ZI CONTAIN THE REAL AND IMAGINARY PARTS, */
00046 /* RESPECTIVELY, OF THE EIGENVECTORS TO BE */
00047 /* BACK TRANSFORMED IN THEIR FIRST M COLUMNS. */
00048
00049 /* ON OUTPUT */
00050
00051 /* ZR AND ZI CONTAIN THE REAL AND IMAGINARY PARTS, */
00052 /* RESPECTIVELY, OF THE TRANSFORMED EIGENVECTORS */
00053 /* IN THEIR FIRST M COLUMNS. */
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 --scale;
00066 zi_dim1 = *nm;
00067 zi_offset = zi_dim1 + 1;
00068 zi -= zi_offset;
00069 zr_dim1 = *nm;
00070 zr_offset = zr_dim1 + 1;
00071 zr -= zr_offset;
00072
00073 /* Function Body */
00074 if (*m == 0) {
00075 goto L200;
00076 }
00077 if (*igh == *low) {
00078 goto L120;
00079 }
00080
00081 i__1 = *igh;
00082 for (i__ = *low; i__ <= i__1; ++i__) {
00083 s = scale[i__];
00084 /* .......... LEFT HAND EIGENVECTORS ARE BACK TRANSFORMED */
00085 /* IF THE FOREGOING STATEMENT IS REPLACED BY */
00086 /* S=1.0D0/SCALE(I). .......... */
00087 i__2 = *m;
00088 for (j = 1; j <= i__2; ++j) {
00089 zr[i__ + j * zr_dim1] *= s;
00090 zi[i__ + j * zi_dim1] *= s;
00091 /* L100: */
00092 }
00093
00094 /* L110: */
00095 }
00096 /* .......... FOR I=LOW-1 STEP -1 UNTIL 1, */
00097 /* IGH+1 STEP 1 UNTIL N DO -- .......... */
00098 L120:
00099 i__1 = *n;
00100 for (ii = 1; ii <= i__1; ++ii) {
00101 i__ = ii;
00102 if (i__ >= *low && i__ <= *igh) {
00103 goto L140;
00104 }
00105 if (i__ < *low) {
00106 i__ = *low - ii;
00107 }
00108 k = (integer) scale[i__];
00109 if (k == i__) {
00110 goto L140;
00111 }
00112
00113 i__2 = *m;
00114 for (j = 1; j <= i__2; ++j) {
00115 s = zr[i__ + j * zr_dim1];
00116 zr[i__ + j * zr_dim1] = zr[k + j * zr_dim1];
00117 zr[k + j * zr_dim1] = s;
00118 s = zi[i__ + j * zi_dim1];
00119 zi[i__ + j * zi_dim1] = zi[k + j * zi_dim1];
00120 zi[k + j * zi_dim1] = s;
00121 /* L130: */
00122 }
00123
00124 L140:
00125 ;
00126 }
00127
00128 L200:
00129 return 0;
00130 } /* cbabk2_ */
|