sspgst.f man page

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.

Referenced By

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

Sat Nov 16 2013 Version 3.4.2 LAPACK