dggbak
dggbak - form the right or left eigenvectors of a real generalized eigenvalue problem A*x = lambda*B*x, by backward transformation on the computed eigenvectors of the balanced pair of matrices output by SGGBAL
SUBROUTINE DGGBAK( JOB, SIDE, N, ILO, IHI, LSCALE, RSCALE, M, V,
* LDV, INFO)
CHARACTER * 1 JOB, SIDE
INTEGER N, ILO, IHI, M, LDV, INFO
DOUBLE PRECISION LSCALE(*), RSCALE(*), V(LDV,*)
SUBROUTINE DGGBAK_64( JOB, SIDE, N, ILO, IHI, LSCALE, RSCALE, M, V,
* LDV, INFO)
CHARACTER * 1 JOB, SIDE
INTEGER*8 N, ILO, IHI, M, LDV, INFO
DOUBLE PRECISION LSCALE(*), RSCALE(*), V(LDV,*)
SUBROUTINE GGBAK( JOB, SIDE, [N], ILO, IHI, LSCALE, RSCALE, [M], V,
* [LDV], [INFO])
CHARACTER(LEN=1) :: JOB, SIDE
INTEGER :: N, ILO, IHI, M, LDV, INFO
REAL(8), DIMENSION(:) :: LSCALE, RSCALE
REAL(8), DIMENSION(:,:) :: V
SUBROUTINE GGBAK_64( JOB, SIDE, [N], ILO, IHI, LSCALE, RSCALE, [M],
* V, [LDV], [INFO])
CHARACTER(LEN=1) :: JOB, SIDE
INTEGER(8) :: N, ILO, IHI, M, LDV, INFO
REAL(8), DIMENSION(:) :: LSCALE, RSCALE
REAL(8), DIMENSION(:,:) :: V
#include <sunperf.h>
void dggbak(char job, char side, int n, int ilo, int ihi, double *lscale, double *rscale, int m, double *v, int ldv, int *info);
void dggbak_64(char job, char side, long n, long ilo, long ihi, double *lscale, double *rscale, long m, double *v, long ldv, long *info);
dggbak forms the right or left eigenvectors of a real generalized
eigenvalue problem A*x = lambda*B*x, by backward transformation on
the computed eigenvectors of the balanced pair of matrices output by
SGGBAL.
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* JOB (input)
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Specifies the type of backward transformation required:
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* SIDE (input)
-
-
* N (input)
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The number of rows of the matrix V. N >= 0.
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* ILO (input)
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The integers ILO and IHI determined by SGGBAL.
1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.
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* IHI (input)
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See the description for ILO.
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* LSCALE (input)
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Details of the permutations and/or scaling factors applied
to the left side of A and B, as returned by SGGBAL.
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* RSCALE (input)
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Details of the permutations and/or scaling factors applied
to the right side of A and B, as returned by SGGBAL.
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* M (input)
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The number of columns of the matrix V. M >= 0.
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* V (input/output)
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On entry, the matrix of right or left eigenvectors to be
transformed, as returned by STGEVC.
On exit, V is overwritten by the transformed eigenvectors.
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* LDV (input)
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The leading dimension of the matrix V. LDV >= max(1,N).
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* INFO (output)
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