chbtrd
chbtrd - reduce a complex Hermitian band matrix A to real symmetric tridiagonal form T by a unitary similarity transformation
SUBROUTINE CHBTRD( VECT, UPLO, N, KD, AB, LDAB, D, E, Q, LDQ, WORK,
* INFO)
CHARACTER * 1 VECT, UPLO
COMPLEX AB(LDAB,*), Q(LDQ,*), WORK(*)
INTEGER N, KD, LDAB, LDQ, INFO
REAL D(*), E(*)
SUBROUTINE CHBTRD_64( VECT, UPLO, N, KD, AB, LDAB, D, E, Q, LDQ,
* WORK, INFO)
CHARACTER * 1 VECT, UPLO
COMPLEX AB(LDAB,*), Q(LDQ,*), WORK(*)
INTEGER*8 N, KD, LDAB, LDQ, INFO
REAL D(*), E(*)
SUBROUTINE HBTRD( VECT, UPLO, [N], KD, AB, [LDAB], D, E, Q, [LDQ],
* [WORK], [INFO])
CHARACTER(LEN=1) :: VECT, UPLO
COMPLEX, DIMENSION(:) :: WORK
COMPLEX, DIMENSION(:,:) :: AB, Q
INTEGER :: N, KD, LDAB, LDQ, INFO
REAL, DIMENSION(:) :: D, E
SUBROUTINE HBTRD_64( VECT, UPLO, [N], KD, AB, [LDAB], D, E, Q, [LDQ],
* [WORK], [INFO])
CHARACTER(LEN=1) :: VECT, UPLO
COMPLEX, DIMENSION(:) :: WORK
COMPLEX, DIMENSION(:,:) :: AB, Q
INTEGER(8) :: N, KD, LDAB, LDQ, INFO
REAL, DIMENSION(:) :: D, E
#include <sunperf.h>
void chbtrd(char vect, char uplo, int n, int kd, complex *ab, int ldab, float *d, float *e, complex *q, int ldq, int *info);
void chbtrd_64(char vect, char uplo, long n, long kd, complex *ab, long ldab, float *d, float *e, complex *q, long ldq, long *info);
chbtrd reduces a complex Hermitian band matrix A to real symmetric
tridiagonal form T by a unitary similarity transformation:
Q**H * A * Q = T.
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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 matrix A. N >= 0.
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* KD (input)
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The number of superdiagonals of the matrix A if UPLO = 'U',
or the number of subdiagonals if UPLO = 'L'. KD >= 0.
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* AB (input/output)
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On entry, the upper or lower triangle of the Hermitian band
matrix A, stored in the first KD+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(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j;
if UPLO = 'L', AB(1+i-j,j) = A(i,j) for j<=i<=min(n,j+kd).
On exit, the diagonal elements of AB are overwritten by the
diagonal elements of the tridiagonal matrix T; if KD > 0, the
elements on the first superdiagonal (if UPLO = 'U') or the
first subdiagonal (if UPLO = 'L') are overwritten by the
off-diagonal elements of T; the rest of AB is overwritten by
values generated during the reduction.
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* LDAB (input)
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The leading dimension of the array AB. LDAB >= KD+1.
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* D (output)
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The diagonal elements of the tridiagonal matrix T.
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* E (output)
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The off-diagonal elements of the tridiagonal matrix T:
E(i) = T(i,i+1) if UPLO = 'U'; E(i) = T(i+1,i) if UPLO = 'L'.
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* Q (input/output)
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On entry, if VECT = 'U', then Q must contain an N-by-N
matrix X; if VECT = 'N' or 'V', then Q need not be set.
On exit:
if VECT = 'V', Q contains the N-by-N unitary matrix Q;
if VECT = 'U', Q contains the product X*Q;
if VECT = 'N', the array Q is not referenced.
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* LDQ (input)
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The leading dimension of the array Q.
LDQ >= 1, and LDQ >= N if VECT = 'V' or 'U'.
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* WORK (workspace)
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dimension(N)
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* INFO (output)
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