chpgst.f (3) Linux Manual Page

chpgst.f –

Synopsis

Functions/Subroutines

subroutine chpgst (ITYPE, UPLO, N, AP, BP, INFO)
CHPGST

Function/Subroutine Documentation

subroutine chpgst (integerITYPE, characterUPLO, integerN, complex, dimension( * )AP, complex, dimension( * )BP, integerINFO)

CHPGST

Purpose:

 CHPGST reduces a complex Hermitian-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**H)*A*inv(U) or inv(L)*A*inv(L**H)

 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**H or L**H*A*L.

 B must have been previously factorized as U**H*U or L*L**H by CPPTRF.

 

Parameters:

ITYPE

 ITYPE is INTEGER

 = 1: compute inv(U**H)*A*inv(U) or inv(L)*A*inv(L**H);

 = 2 or 3: compute U*A*U**H or L**H*A*L.

UPLO

 UPLO is CHARACTER*1

 = ‘U’: Upper triangle of A is stored and B is factored as

 U**H*U;

 = ‘L’: Lower triangle of A is stored and B is factored as

 L*L**H.

N

 N is INTEGER

 The order of the matrices A and B. N >= 0.

AP

 AP is COMPLEX array, dimension (N*(N+1)/2)

 On entry, the upper or lower triangle of the Hermitian 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 COMPLEX 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 CPPTRF.

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:

November 2011

Definition at line 114 of file chpgst.f.

Author

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