LAPACK  3.5.0
LAPACK: Linear Algebra PACKage
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dbdt02.f File Reference

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Functions/Subroutines

subroutine dbdt02 (M, N, B, LDB, C, LDC, U, LDU, WORK, RESID)
 DBDT02 More...
 

Function/Subroutine Documentation

subroutine dbdt02 ( integer  M,
integer  N,
double precision, dimension( ldb, * )  B,
integer  LDB,
double precision, dimension( ldc, * )  C,
integer  LDC,
double precision, dimension( ldu, * )  U,
integer  LDU,
double precision, dimension( * )  WORK,
double precision  RESID 
)

DBDT02

Purpose:
 DBDT02 tests the change of basis C = U' * B by computing the residual

    RESID = norm( B - U * C ) / ( max(m,n) * norm(B) * EPS ),

 where B and C are M by N matrices, U is an M by M orthogonal matrix,
 and EPS is the machine precision.
Parameters
[in]M
          M is INTEGER
          The number of rows of the matrices B and C and the order of
          the matrix Q.
[in]N
          N is INTEGER
          The number of columns of the matrices B and C.
[in]B
          B is DOUBLE PRECISION array, dimension (LDB,N)
          The m by n matrix B.
[in]LDB
          LDB is INTEGER
          The leading dimension of the array B.  LDB >= max(1,M).
[in]C
          C is DOUBLE PRECISION array, dimension (LDC,N)
          The m by n matrix C, assumed to contain U' * B.
[in]LDC
          LDC is INTEGER
          The leading dimension of the array C.  LDC >= max(1,M).
[in]U
          U is DOUBLE PRECISION array, dimension (LDU,M)
          The m by m orthogonal matrix U.
[in]LDU
          LDU is INTEGER
          The leading dimension of the array U.  LDU >= max(1,M).
[out]WORK
          WORK is DOUBLE PRECISION array, dimension (M)
[out]RESID
          RESID is DOUBLE PRECISION
          RESID = norm( B - U * C ) / ( max(m,n) * norm(B) * EPS ),
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date
November 2011

Definition at line 112 of file dbdt02.f.

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