LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

Go to the source code of this file.
Functions/Subroutines  
subroutine  dsbgv (JOBZ, UPLO, N, KA, KB, AB, LDAB, BB, LDBB, W, Z, LDZ, WORK, INFO) 
DSBGST 
subroutine dsbgv  (  character  JOBZ, 
character  UPLO,  
integer  N,  
integer  KA,  
integer  KB,  
double precision, dimension( ldab, * )  AB,  
integer  LDAB,  
double precision, dimension( ldbb, * )  BB,  
integer  LDBB,  
double precision, dimension( * )  W,  
double precision, dimension( ldz, * )  Z,  
integer  LDZ,  
double precision, dimension( * )  WORK,  
integer  INFO  
) 
DSBGST
Download DSBGV + dependencies [TGZ] [ZIP] [TXT]DSBGV computes all the eigenvalues, and optionally, the eigenvectors of a real generalized symmetricdefinite banded eigenproblem, of the form A*x=(lambda)*B*x. Here A and B are assumed to be symmetric and banded, and B is also positive definite.
[in]  JOBZ  JOBZ is CHARACTER*1 = 'N': Compute eigenvalues only; = 'V': Compute eigenvalues and eigenvectors. 
[in]  UPLO  UPLO is CHARACTER*1 = 'U': Upper triangles of A and B are stored; = 'L': Lower triangles of A and B are stored. 
[in]  N  N is INTEGER The order of the matrices A and B. N >= 0. 
[in]  KA  KA is INTEGER The number of superdiagonals of the matrix A if UPLO = 'U', or the number of subdiagonals if UPLO = 'L'. KA >= 0. 
[in]  KB  KB is INTEGER The number of superdiagonals of the matrix B if UPLO = 'U', or the number of subdiagonals if UPLO = 'L'. KB >= 0. 
[in,out]  AB  AB is DOUBLE PRECISION array, dimension (LDAB, N) On entry, the upper or lower triangle of the symmetric band matrix A, stored in the first ka+1 rows of the array. The jth column of A is stored in the jth column of the array AB as follows: if UPLO = 'U', AB(ka+1+ij,j) = A(i,j) for max(1,jka)<=i<=j; if UPLO = 'L', AB(1+ij,j) = A(i,j) for j<=i<=min(n,j+ka). On exit, the contents of AB are destroyed. 
[in]  LDAB  LDAB is INTEGER The leading dimension of the array AB. LDAB >= KA+1. 
[in,out]  BB  BB is DOUBLE PRECISION array, dimension (LDBB, N) On entry, the upper or lower triangle of the symmetric band matrix B, stored in the first kb+1 rows of the array. The jth column of B is stored in the jth column of the array BB as follows: if UPLO = 'U', BB(kb+1+ij,j) = B(i,j) for max(1,jkb)<=i<=j; if UPLO = 'L', BB(1+ij,j) = B(i,j) for j<=i<=min(n,j+kb). On exit, the factor S from the split Cholesky factorization B = S**T*S, as returned by DPBSTF. 
[in]  LDBB  LDBB is INTEGER The leading dimension of the array BB. LDBB >= KB+1. 
[out]  W  W is DOUBLE PRECISION array, dimension (N) If INFO = 0, the eigenvalues in ascending order. 
[out]  Z  Z is DOUBLE PRECISION array, dimension (LDZ, N) If JOBZ = 'V', then if INFO = 0, Z contains the matrix Z of eigenvectors, with the ith column of Z holding the eigenvector associated with W(i). The eigenvectors are normalized so that Z**T*B*Z = I. If JOBZ = 'N', then Z is not referenced. 
[in]  LDZ  LDZ is INTEGER The leading dimension of the array Z. LDZ >= 1, and if JOBZ = 'V', LDZ >= N. 
[out]  WORK  WORK is DOUBLE PRECISION array, dimension (3*N) 
[out]  INFO  INFO is INTEGER = 0: successful exit < 0: if INFO = i, the ith argument had an illegal value > 0: if INFO = i, and i is: <= N: the algorithm failed to converge: i offdiagonal elements of an intermediate tridiagonal form did not converge to zero; > N: if INFO = N + i, for 1 <= i <= N, then DPBSTF returned INFO = i: B is not positive definite. The factorization of B could not be completed and no eigenvalues or eigenvectors were computed. 
Definition at line 177 of file dsbgv.f.