TESTING/EIG/sbdt01.f(3)

NAME
TESTING/EIG/sbdt01.f

SYNOPSIS

  Functions/Subroutines
subroutine sbdt01 (m, n, kd, a, lda, q, ldq, d, e, pt, ldpt, work, resid)
SBDT01

Function/Subroutine Documentation

  subroutine sbdt01 (integer m, integer n, integer kd, real, dimension( lda, * ) a, integer lda, real, dimension( ldq, * ) q, integer ldq, real, dimension( * ) d, real, dimension( * ) e, real, dimension( ldpt, * ) pt, integer ldpt, real, dimension( * ) work, real resid)

SBDT01

Purpose:

     SBDT01 reconstructs a general matrix A from its bidiagonal form
        A = Q * B * P**T
     where Q (m by min(m,n)) and P**T (min(m,n) by n) are orthogonal
     matrices and B is bidiagonal.
     The test ratio to test the reduction is
        RESID = norm(A - Q * B * P**T) / ( n * norm(A) * EPS )
     where EPS is the machine precision.

Parameters
    M

              M is INTEGER
              The number of rows of the matrices A and Q.

    N

              N is INTEGER
              The number of columns of the matrices A and P**T.

    KD

              KD is INTEGER
              If KD = 0, B is diagonal and the array E is not referenced.
              If KD = 1, the reduction was performed by xGEBRD; B is upper
              bidiagonal if M >= N, and lower bidiagonal if M < N.
              If KD = -1, the reduction was performed by xGBBRD; B is
              always upper bidiagonal.

    A

              A is REAL array, dimension (LDA,N)
              The m by n matrix A.

    LDA

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

    Q

              Q is REAL array, dimension (LDQ,N)
              The m by min(m,n) orthogonal matrix Q in the reduction
              A = Q * B * P**T.

    LDQ

              LDQ is INTEGER
              The leading dimension of the array Q.  LDQ >= max(1,M).

    D

              D is REAL array, dimension (min(M,N))
              The diagonal elements of the bidiagonal matrix B.

    E

              E is REAL array, dimension (min(M,N)-1)
              The superdiagonal elements of the bidiagonal matrix B if
              m >= n, or the subdiagonal elements of B if m < n.

    PT

              PT is REAL array, dimension (LDPT,N)
              The min(m,n) by n orthogonal matrix P**T in the reduction
              A = Q * B * P**T.

    LDPT

              LDPT is INTEGER
              The leading dimension of the array PT.
              LDPT >= max(1,min(M,N)).

    WORK

              WORK is REAL array, dimension (M+N)

    RESID

              RESID is REAL
              The test ratio:
              norm(A - Q * B * P**T) / ( n * norm(A) * EPS )

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 139 of file sbdt01.f.

Author

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