dspgst.f - Man Page
Synopsis
Functions/Subroutines
subroutine dspgst (ITYPE, UPLO, N, AP, BP, INFO)
DSPGST
Function/Subroutine Documentation
subroutine dspgst (integer ITYPE, character UPLO, integer N, double precision, dimension( * ) AP, double precision, dimension( * ) BP, integer INFO)
DSPGST
Purpose:
DSPGST reduces a real symmetric-definite generalized eigenproblem to standard form, using packed storage. If ITYPE = 1, the problem is A*x = lambda*B*x, and A is overwritten by inv(U**T)*A*inv(U) or inv(L)*A*inv(L**T) If ITYPE = 2 or 3, the problem is A*B*x = lambda*x or B*A*x = lambda*x, and A is overwritten by U*A*U**T or L**T*A*L. B must have been previously factorized as U**T*U or L*L**T by DPPTRF.
- Parameters:
ITYPE
ITYPE is INTEGER = 1: compute inv(U**T)*A*inv(U) or inv(L)*A*inv(L**T); = 2 or 3: compute U*A*U**T or L**T*A*L.
UPLO
UPLO is CHARACTER*1 = 'U': Upper triangle of A is stored and B is factored as U**T*U; = 'L': Lower triangle of A is stored and B is factored as L*L**T.
N
N is INTEGER The order of the matrices A and B. N >= 0.
AP
AP is DOUBLE PRECISION array, dimension (N*(N+1)/2) On entry, the upper or lower triangle of the symmetric matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n. On exit, if INFO = 0, the transformed matrix, stored in the same format as A.
BP
BP is DOUBLE PRECISION array, dimension (N*(N+1)/2) The triangular factor from the Cholesky factorization of B, stored in the same format as A, as returned by DPPTRF.
INFO
INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value
- Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
- Date:
December 2016
Definition at line 115 of file dspgst.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Referenced By
The man page dspgst(3) is an alias of dspgst.f(3).
Tue Nov 14 2017 Version 3.8.0 LAPACK