Scroll to navigation

sspgst.f(3) LAPACK sspgst.f(3)

NAME

sspgst.f -

SYNOPSIS

Functions/Subroutines


subroutine sspgst (ITYPE, UPLO, N, AP, BP, INFO)
SSPGST

Function/Subroutine Documentation

subroutine sspgst (integerITYPE, characterUPLO, integerN, real, dimension( * )AP, real, dimension( * )BP, integerINFO)

SSPGST

Purpose:


SSPGST 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 SPPTRF.

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 REAL 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 REAL 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 SPPTRF.

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 sspgst.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Tue Sep 25 2012 Version 3.4.2