TESTING/EIG/dsgt01.f(3)

NAME
TESTING/EIG/dsgt01.f

SYNOPSIS

  Functions/Subroutines
subroutine dsgt01 (itype, uplo, n, m, a, lda, b, ldb, z, ldz, d, work, result)
DSGT01

Function/Subroutine Documentation

  subroutine dsgt01 (integer itype, character uplo, integer n, integer m, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( ldb, * ) b, integer ldb, double precision, dimension( ldz, * ) z, integer ldz, double precision, dimension( * ) d, double precision, dimension( * ) work, double precision, dimension( * ) result)

DSGT01

Purpose:

    !>
    !> DDGT01 checks a decomposition of the form
    !>
    !>    A Z   =  B Z D or
    !>    A B Z =  Z D or
    !>    B A Z =  Z D
    !>
    !> where A is a symmetric matrix, B is
    !> symmetric positive definite, Z is orthogonal, and D is diagonal.
    !>
    !> One of the following test ratios is computed:
    !>
    !> ITYPE = 1:  RESULT(1) = | A Z - B Z D | / ( |A| |Z| n ulp )
    !>
    !> ITYPE = 2:  RESULT(1) = | A B Z - Z D | / ( |A| |Z| n ulp )
    !>
    !> ITYPE = 3:  RESULT(1) = | B A Z - Z D | / ( |A| |Z| n ulp )
    !>

Parameters
    ITYPE

    !>          ITYPE is INTEGER
    !>          The form of the symmetric generalized eigenproblem.
    !>          = 1:  A*z = (lambda)*B*z
    !>          = 2:  A*B*z = (lambda)*z
    !>          = 3:  B*A*z = (lambda)*z
    !>

    UPLO

    !>          UPLO is CHARACTER*1
    !>          Specifies whether the upper or lower triangular part of the
    !>          symmetric matrices A and B is stored.
    !>          = 'U':  Upper triangular
    !>          = 'L':  Lower triangular
    !>

    N

    !>          N is INTEGER
    !>          The order of the matrix A.  N >= 0.
    !>

    M

    !>          M is INTEGER
    !>          The number of eigenvalues found.  0 <= M <= N.
    !>

    A

    !>          A is DOUBLE PRECISION array, dimension (LDA, N)
    !>          The original symmetric matrix 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 original symmetric positive definite matrix B.
    !>

    LDB

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

    Z

    !>          Z is DOUBLE PRECISION array, dimension (LDZ, M)
    !>          The computed eigenvectors of the generalized eigenproblem.
    !>

    LDZ

    !>          LDZ is INTEGER
    !>          The leading dimension of the array Z.  LDZ >= max(1,N).
    !>

    D

    !>          D is DOUBLE PRECISION array, dimension (M)
    !>          The computed eigenvalues of the generalized eigenproblem.
    !>

    WORK

    !>          WORK is DOUBLE PRECISION array, dimension (N*N)
    !>

    RESULT

    !>          RESULT is DOUBLE PRECISION array, dimension (1)
    !>          The test ratio as described above.
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 144 of file dsgt01.f.

Author

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