TESTING/EIG/dbdt01.f(3)    Library Functions Manual    TESTING/EIG/dbdt01.f(3)

NAME
       TESTING/EIG/dbdt01.f

SYNOPSIS
   Functions/Subroutines
       subroutine dbdt01 (m, n, kd, a, lda, q, ldq, d, e, pt, ldpt, work,
           resid)
           DBDT01

Function/Subroutine Documentation
   subroutine dbdt01 (integer m, integer n, integer kd, double precision,
       dimension( lda, * ) a, integer lda, double precision, dimension( ldq, *
       ) q, integer ldq, double precision, dimension( * ) d, double precision,
       dimension( * ) e, double precision, dimension( ldpt, * ) pt, integer
       ldpt, double precision, dimension( * ) work, double precision resid)
       DBDT01

       Purpose:


            DBDT01 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 DOUBLE PRECISION 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 DOUBLE PRECISION 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 DOUBLE PRECISION array, dimension (min(M,N))
                     The diagonal elements of the bidiagonal matrix B.

           E

                     E is DOUBLE PRECISION 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 DOUBLE PRECISION 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 DOUBLE PRECISION array, dimension (M+N)

           RESID

                     RESID is DOUBLE PRECISION
                     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 dbdt01.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0         TESTING/EIG/dbdt01.f(3)