chbgst.f(3) LAPACK chbgst.f(3)NAMEchbgst.f-
subroutine chbgst (VECT, UPLO, N, KA, KB, AB, LDAB, BB, LDBB, X, LDX,
WORK, RWORK, INFO)
subroutine chbgst (characterVECT, characterUPLO, integerN, integerKA,
integerKB, complex, dimension( ldab, * )AB, integerLDAB, complex,
dimension( ldbb, * )BB, integerLDBB, complex, dimension( ldx, * )X,
integerLDX, complex, dimension( * )WORK, real, dimension( * )RWORK,
CHBGST reduces a complex Hermitian-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**H*S by CPBSTF, using a
split Cholesky factorization. A is overwritten by C = X**H*A*X, where
X = S**(-1)*Q and Q is a unitary matrix chosen to preserve the
bandwidth of A.
VECT is CHARACTER*1
= 'N': do not form the transformation matrix X;
= 'V': form X.
UPLO is CHARACTER*1
= 'U': Upper triangle of A is stored;
= 'L': Lower triangle of A is stored.
N is INTEGER
The order of the matrices A and B. N >= 0.
KA is INTEGER
The number of superdiagonals of the matrix A if UPLO = 'U',
or the number of subdiagonals if UPLO = 'L'. KA >= 0.
KB is INTEGER
The number of superdiagonals of the matrix B if UPLO = 'U',
or the number of subdiagonals if UPLO = 'L'. KA >= KB >= 0.
AB is COMPLEX array, dimension (LDAB,N)
On entry, the upper or lower triangle of the Hermitian 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
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**H*A*X, stored in the same
format as A.
LDAB is INTEGER
The leading dimension of the array AB. LDAB >= KA+1.
BB is COMPLEX array, dimension (LDBB,N)
The banded factor S from the split Cholesky factorization of
B, as returned by CPBSTF, stored in the first kb+1 rows of
LDBB is INTEGER
The leading dimension of the array BB. LDBB >= KB+1.
X is COMPLEX array, dimension (LDX,N)
If VECT = 'V', the n-by-n matrix X.
If VECT = 'N', the array X is not referenced.
LDX is INTEGER
The leading dimension of the array X.
LDX >= max(1,N) if VECT = 'V'; LDX >= 1 otherwise.
WORK is COMPLEX array, dimension (N)
RWORK is REAL array, dimension (N)
INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value.
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
Definition at line 165 of file chbgst.f.
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 chbgst.f(3)