ssbgst
ssbgst - reduce a real symmetric-definite banded generalized eigenproblem A*x = lambda*B*x to standard form C*y = lambda*y,
SUBROUTINE SSBGST( VECT, UPLO, N, KA, KB, AB, LDAB, BB, LDBB, X,
* LDX, WORK, INFO)
CHARACTER * 1 VECT, UPLO
INTEGER N, KA, KB, LDAB, LDBB, LDX, INFO
REAL AB(LDAB,*), BB(LDBB,*), X(LDX,*), WORK(*)
SUBROUTINE SSBGST_64( VECT, UPLO, N, KA, KB, AB, LDAB, BB, LDBB, X,
* LDX, WORK, INFO)
CHARACTER * 1 VECT, UPLO
INTEGER*8 N, KA, KB, LDAB, LDBB, LDX, INFO
REAL AB(LDAB,*), BB(LDBB,*), X(LDX,*), WORK(*)
SUBROUTINE SBGST( VECT, UPLO, [N], KA, KB, AB, [LDAB], BB, [LDBB],
* X, [LDX], [WORK], [INFO])
CHARACTER(LEN=1) :: VECT, UPLO
INTEGER :: N, KA, KB, LDAB, LDBB, LDX, INFO
REAL, DIMENSION(:) :: WORK
REAL, DIMENSION(:,:) :: AB, BB, X
SUBROUTINE SBGST_64( VECT, UPLO, [N], KA, KB, AB, [LDAB], BB, [LDBB],
* X, [LDX], [WORK], [INFO])
CHARACTER(LEN=1) :: VECT, UPLO
INTEGER(8) :: N, KA, KB, LDAB, LDBB, LDX, INFO
REAL, DIMENSION(:) :: WORK
REAL, DIMENSION(:,:) :: AB, BB, X
#include <sunperf.h>
void ssbgst(char vect, char uplo, int n, int ka, int kb, float *ab, int ldab, float *bb, int ldbb, float *x, int ldx, int *info);
void ssbgst_64(char vect, char uplo, long n, long ka, long kb, float *ab, long ldab, float *bb, long ldbb, float *x, long ldx, long *info);
ssbgst reduces a real symmetric-definite banded generalized
eigenproblem A*x = lambda*B*x to standard form C*y = lambda*y,
such that C has the same bandwidth as A.
B must have been previously factorized as S**T*S by SPBSTF, using a
split Cholesky factorization. A is overwritten by C = X**T*A*X, where
X = S**(-1)*Q and Q is an orthogonal matrix chosen to preserve the
bandwidth of A.
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* VECT (input)
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* UPLO (input)
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* N (input)
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The order of the matrices A and B. N >= 0.
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* KA (input)
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The number of superdiagonals of the matrix A if UPLO = 'U',
or the number of subdiagonals if UPLO = 'L'. KA >= 0.
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* KB (input)
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The number of superdiagonals of the matrix B if UPLO = 'U',
or the number of subdiagonals if UPLO = 'L'. KA >= KB >= 0.
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* AB (input/output)
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On entry, the upper or lower triangle of the symmetric band
matrix A, stored in the first ka+1 rows of the array. The
j-th column of A is stored in the j-th column of the array AB
as follows:
if UPLO = 'U', AB(ka+1+i-j,j) = A(i,j) for max(1,j-ka)<=i<=j;
if UPLO = 'L', AB(1+i-j,j) = A(i,j) for j<=i<=min(n,j+ka).
On exit, the transformed matrix X**T*A*X, stored in the same
format as A.
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* LDAB (input)
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The leading dimension of the array AB. LDAB >= KA+1.
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* BB (input)
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The banded factor S from the split Cholesky factorization of
B, as returned by SPBSTF, stored in the first KB+1 rows of
the array.
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* LDBB (input)
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The leading dimension of the array BB. LDBB >= KB+1.
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* X (output)
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If VECT = 'V', the n-by-n matrix X.
If VECT = 'N', the array X is not referenced.
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* LDX (input)
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The leading dimension of the array X.
LDX >= max(1,N) if VECT = 'V'; LDX >= 1 otherwise.
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* WORK (workspace)
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dimension(2*N)
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* INFO (output)
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