Scroll to navigation

CHEGS2(1) LAPACK routine (version 3.2) CHEGS2(1)

NAME

CHEGS2 - reduces a complex Hermitian-definite generalized eigenproblem to standard form

SYNOPSIS

ITYPE, UPLO, N, A, LDA, B, LDB, INFO )

CHARACTER UPLO INTEGER INFO, ITYPE, LDA, LDB, N COMPLEX A( LDA, * ), B( LDB, * )

PURPOSE

CHEGS2 reduces a complex Hermitian-definite generalized eigenproblem to standard form. If ITYPE = 1, the problem is A*x = lambda*B*x,
and A is overwritten by inv(U')*A*inv(U) or inv(L)*A*inv(L') 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` or L'*A*L. B must have been previously factorized as U'*U or L*L' by CPOTRF.

ARGUMENTS

= 1: compute inv(U')*A*inv(U) or inv(L)*A*inv(L');
= 2 or 3: compute U*A*U' or L'*A*L.
Specifies whether the upper or lower triangular part of the Hermitian matrix A is stored, and how B has been factorized. = 'U': Upper triangular
= 'L': Lower triangular
The order of the matrices A and B. N >= 0.
On entry, the Hermitian matrix A. If UPLO = 'U', the leading n by n upper triangular part of A contains the upper triangular part of the matrix A, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading n by n lower triangular part of A contains the lower triangular part of the matrix A, and the strictly upper triangular part of A is not referenced. On exit, if INFO = 0, the transformed matrix, stored in the same format as A.
The leading dimension of the array A. LDA >= max(1,N).
The triangular factor from the Cholesky factorization of B, as returned by CPOTRF.
The leading dimension of the array B. LDB >= max(1,N).
= 0: successful exit.
< 0: if INFO = -i, the i-th argument had an illegal value.
November 2008 LAPACK routine (version 3.2)