dspgst.f man page

dspgst.f —

Synopsis

Functions/Subroutines

subroutine dspgst (ITYPE, UPLO, N, AP, BP, INFO)
DSPGST

Function/Subroutine Documentation

subroutine dspgst (integerITYPE, characterUPLO, integerN, double precision, dimension( * )AP, double precision, dimension( * )BP, integerINFO)

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:

November 2011

Definition at line 114 of file dspgst.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

dspgst(3) is an alias of dspgst.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK