dsygst.f

Section: LAPACK (3)
Updated: Tue Nov 14 2017
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NAME

dsygst.f  

SYNOPSIS


 

Functions/Subroutines


subroutine dsygst (ITYPE, UPLO, N, A, LDA, B, LDB, INFO)
DSYGST  

Function/Subroutine Documentation

 

subroutine dsygst (integer ITYPE, character UPLO, integer N, double precision, dimension( lda, * ) A, integer LDA, double precision, dimension( ldb, * ) B, integer LDB, integer INFO)

DSYGST

Purpose:

 DSYGST reduces a real symmetric-definite generalized eigenproblem
 to standard form.

 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 DPOTRF.


 

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.


A

          A is DOUBLE PRECISION array, dimension (LDA,N)
          On entry, the symmetric 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.


LDA

          LDA is INTEGER
          The leading dimension of the array A.  LDA >= max(1,N).


B

          B is DOUBLE PRECISION array, dimension (LDB,N)
          The triangular factor from the Cholesky factorization of B,
          as returned by DPOTRF.


LDB

          LDB is INTEGER
          The leading dimension of the array B.  LDB >= max(1,N).


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:

December 2016

Definition at line 129 of file dsygst.f.  

Author

Generated automatically by Doxygen for LAPACK from the source code.


 

Index

NAME
SYNOPSIS
Functions/Subroutines
Function/Subroutine Documentation
subroutine dsygst (integer ITYPE, character UPLO, integer N, double precision, dimension( lda, * ) A, integer LDA, double precision, dimension( ldb, * ) B, integer LDB, integer INFO)
Author
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