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OpenBLAS/lapack-netlib/TESTING/EIG/sgqrts.f

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*> \brief \b SGQRTS
*
* =========== DOCUMENTATION ===========
*
* Online html documentation available at
* http://www.netlib.org/lapack/explore-html/
*
* Definition:
* ===========
*
* SUBROUTINE SGQRTS( N, M, P, A, AF, Q, R, LDA, TAUA, B, BF, Z, T,
* BWK, LDB, TAUB, WORK, LWORK, RWORK, RESULT )
*
* .. Scalar Arguments ..
* INTEGER LDA, LDB, LWORK, M, P, N
* ..
* .. Array Arguments ..
* REAL A( LDA, * ), AF( LDA, * ), R( LDA, * ),
* $ Q( LDA, * ), B( LDB, * ), BF( LDB, * ),
* $ T( LDB, * ), Z( LDB, * ), BWK( LDB, * ),
* $ TAUA( * ), TAUB( * ), RESULT( 4 ),
* $ RWORK( * ), WORK( LWORK )
* ..
*
*
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> SGQRTS tests SGGQRF, which computes the GQR factorization of an
*> N-by-M matrix A and a N-by-P matrix B: A = Q*R and B = Q*T*Z.
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in] N
*> \verbatim
*> N is INTEGER
*> The number of rows of the matrices A and B. N >= 0.
*> \endverbatim
*>
*> \param[in] M
*> \verbatim
*> M is INTEGER
*> The number of columns of the matrix A. M >= 0.
*> \endverbatim
*>
*> \param[in] P
*> \verbatim
*> P is INTEGER
*> The number of columns of the matrix B. P >= 0.
*> \endverbatim
*>
*> \param[in] A
*> \verbatim
*> A is REAL array, dimension (LDA,M)
*> The N-by-M matrix A.
*> \endverbatim
*>
*> \param[out] AF
*> \verbatim
*> AF is REAL array, dimension (LDA,N)
*> Details of the GQR factorization of A and B, as returned
*> by SGGQRF, see SGGQRF for further details.
*> \endverbatim
*>
*> \param[out] Q
*> \verbatim
*> Q is REAL array, dimension (LDA,N)
*> The M-by-M orthogonal matrix Q.
*> \endverbatim
*>
*> \param[out] R
*> \verbatim
*> R is REAL array, dimension (LDA,MAX(M,N))
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*> LDA is INTEGER
*> The leading dimension of the arrays A, AF, R and Q.
*> LDA >= max(M,N).
*> \endverbatim
*>
*> \param[out] TAUA
*> \verbatim
*> TAUA is REAL array, dimension (min(M,N))
*> The scalar factors of the elementary reflectors, as returned
*> by SGGQRF.
*> \endverbatim
*>
*> \param[in] B
*> \verbatim
*> B is REAL array, dimension (LDB,P)
*> On entry, the N-by-P matrix A.
*> \endverbatim
*>
*> \param[out] BF
*> \verbatim
*> BF is REAL array, dimension (LDB,N)
*> Details of the GQR factorization of A and B, as returned
*> by SGGQRF, see SGGQRF for further details.
*> \endverbatim
*>
*> \param[out] Z
*> \verbatim
*> Z is REAL array, dimension (LDB,P)
*> The P-by-P orthogonal matrix Z.
*> \endverbatim
*>
*> \param[out] T
*> \verbatim
*> T is REAL array, dimension (LDB,max(P,N))
*> \endverbatim
*>
*> \param[out] BWK
*> \verbatim
*> BWK is REAL array, dimension (LDB,N)
*> \endverbatim
*>
*> \param[in] LDB
*> \verbatim
*> LDB is INTEGER
*> The leading dimension of the arrays B, BF, Z and T.
*> LDB >= max(P,N).
*> \endverbatim
*>
*> \param[out] TAUB
*> \verbatim
*> TAUB is REAL array, dimension (min(P,N))
*> The scalar factors of the elementary reflectors, as returned
*> by SGGRQF.
*> \endverbatim
*>
*> \param[out] WORK
*> \verbatim
*> WORK is REAL array, dimension (LWORK)
*> \endverbatim
*>
*> \param[in] LWORK
*> \verbatim
*> LWORK is INTEGER
*> The dimension of the array WORK, LWORK >= max(N,M,P)**2.
*> \endverbatim
*>
*> \param[out] RWORK
*> \verbatim
*> RWORK is REAL array, dimension (max(N,M,P))
*> \endverbatim
*>
*> \param[out] RESULT
*> \verbatim
*> RESULT is REAL array, dimension (4)
*> The test ratios:
*> RESULT(1) = norm( R - Q'*A ) / ( MAX(M,N)*norm(A)*ULP)
*> RESULT(2) = norm( T*Z - Q'*B ) / (MAX(P,N)*norm(B)*ULP)
*> RESULT(3) = norm( I - Q'*Q ) / ( M*ULP )
*> RESULT(4) = norm( I - Z'*Z ) / ( P*ULP )
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \ingroup single_eig
*
* =====================================================================
SUBROUTINE SGQRTS( N, M, P, A, AF, Q, R, LDA, TAUA, B, BF, Z, T,
$ BWK, LDB, TAUB, WORK, LWORK, RWORK, RESULT )
*
* -- LAPACK test routine --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*
* .. Scalar Arguments ..
INTEGER LDA, LDB, LWORK, M, P, N
* ..
* .. Array Arguments ..
REAL A( LDA, * ), AF( LDA, * ), R( LDA, * ),
$ Q( LDA, * ), B( LDB, * ), BF( LDB, * ),
$ T( LDB, * ), Z( LDB, * ), BWK( LDB, * ),
$ TAUA( * ), TAUB( * ), RESULT( 4 ),
$ RWORK( * ), WORK( LWORK )
* ..
*
* =====================================================================
*
* .. Parameters ..
REAL ZERO, ONE
PARAMETER ( ZERO = 0.0E+0, ONE = 1.0E+0 )
REAL ROGUE
PARAMETER ( ROGUE = -1.0E+10 )
* ..
* .. Local Scalars ..
INTEGER INFO
REAL ANORM, BNORM, ULP, UNFL, RESID
* ..
* .. External Functions ..
REAL SLAMCH, SLANGE, SLANSY
EXTERNAL SLAMCH, SLANGE, SLANSY
* ..
* .. External Subroutines ..
EXTERNAL SGEMM, SLACPY, SLASET, SORGQR,
$ SORGRQ, SSYRK
* ..
* .. Intrinsic Functions ..
INTRINSIC MAX, MIN, REAL
* ..
* .. Executable Statements ..
*
ULP = SLAMCH( 'Precision' )
UNFL = SLAMCH( 'Safe minimum' )
*
* Copy the matrix A to the array AF.
*
CALL SLACPY( 'Full', N, M, A, LDA, AF, LDA )
CALL SLACPY( 'Full', N, P, B, LDB, BF, LDB )
*
ANORM = MAX( SLANGE( '1', N, M, A, LDA, RWORK ), UNFL )
BNORM = MAX( SLANGE( '1', N, P, B, LDB, RWORK ), UNFL )
*
* Factorize the matrices A and B in the arrays AF and BF.
*
CALL SGGQRF( N, M, P, AF, LDA, TAUA, BF, LDB, TAUB, WORK,
$ LWORK, INFO )
*
* Generate the N-by-N matrix Q
*
CALL SLASET( 'Full', N, N, ROGUE, ROGUE, Q, LDA )
CALL SLACPY( 'Lower', N-1, M, AF( 2,1 ), LDA, Q( 2,1 ), LDA )
CALL SORGQR( N, N, MIN( N, M ), Q, LDA, TAUA, WORK, LWORK, INFO )
*
* Generate the P-by-P matrix Z
*
CALL SLASET( 'Full', P, P, ROGUE, ROGUE, Z, LDB )
IF( N.LE.P ) THEN
IF( N.GT.0 .AND. N.LT.P )
$ CALL SLACPY( 'Full', N, P-N, BF, LDB, Z( P-N+1, 1 ), LDB )
IF( N.GT.1 )
$ CALL SLACPY( 'Lower', N-1, N-1, BF( 2, P-N+1 ), LDB,
$ Z( P-N+2, P-N+1 ), LDB )
ELSE
IF( P.GT.1)
$ CALL SLACPY( 'Lower', P-1, P-1, BF( N-P+2, 1 ), LDB,
$ Z( 2, 1 ), LDB )
END IF
CALL SORGRQ( P, P, MIN( N, P ), Z, LDB, TAUB, WORK, LWORK, INFO )
*
* Copy R
*
CALL SLASET( 'Full', N, M, ZERO, ZERO, R, LDA )
CALL SLACPY( 'Upper', N, M, AF, LDA, R, LDA )
*
* Copy T
*
CALL SLASET( 'Full', N, P, ZERO, ZERO, T, LDB )
IF( N.LE.P ) THEN
CALL SLACPY( 'Upper', N, N, BF( 1, P-N+1 ), LDB, T( 1, P-N+1 ),
$ LDB )
ELSE
CALL SLACPY( 'Full', N-P, P, BF, LDB, T, LDB )
CALL SLACPY( 'Upper', P, P, BF( N-P+1, 1 ), LDB, T( N-P+1, 1 ),
$ LDB )
END IF
*
* Compute R - Q'*A
*
CALL SGEMM( 'Transpose', 'No transpose', N, M, N, -ONE, Q, LDA, A,
$ LDA, ONE, R, LDA )
*
* Compute norm( R - Q'*A ) / ( MAX(M,N)*norm(A)*ULP ) .
*
RESID = SLANGE( '1', N, M, R, LDA, RWORK )
IF( ANORM.GT.ZERO ) THEN
RESULT( 1 ) = ( ( RESID / REAL( MAX(1,M,N) ) ) / ANORM ) / ULP
ELSE
RESULT( 1 ) = ZERO
END IF
*
* Compute T*Z - Q'*B
*
CALL SGEMM( 'No Transpose', 'No transpose', N, P, P, ONE, T, LDB,
$ Z, LDB, ZERO, BWK, LDB )
CALL SGEMM( 'Transpose', 'No transpose', N, P, N, -ONE, Q, LDA,
$ B, LDB, ONE, BWK, LDB )
*
* Compute norm( T*Z - Q'*B ) / ( MAX(P,N)*norm(A)*ULP ) .
*
RESID = SLANGE( '1', N, P, BWK, LDB, RWORK )
IF( BNORM.GT.ZERO ) THEN
RESULT( 2 ) = ( ( RESID / REAL( MAX(1,P,N ) ) )/BNORM ) / ULP
ELSE
RESULT( 2 ) = ZERO
END IF
*
* Compute I - Q'*Q
*
CALL SLASET( 'Full', N, N, ZERO, ONE, R, LDA )
CALL SSYRK( 'Upper', 'Transpose', N, N, -ONE, Q, LDA, ONE, R,
$ LDA )
*
* Compute norm( I - Q'*Q ) / ( N * ULP ) .
*
RESID = SLANSY( '1', 'Upper', N, R, LDA, RWORK )
RESULT( 3 ) = ( RESID / REAL( MAX( 1, N ) ) ) / ULP
*
* Compute I - Z'*Z
*
CALL SLASET( 'Full', P, P, ZERO, ONE, T, LDB )
CALL SSYRK( 'Upper', 'Transpose', P, P, -ONE, Z, LDB, ONE, T,
$ LDB )
*
* Compute norm( I - Z'*Z ) / ( P*ULP ) .
*
RESID = SLANSY( '1', 'Upper', P, T, LDB, RWORK )
RESULT( 4 ) = ( RESID / REAL( MAX( 1, P ) ) ) / ULP
*
RETURN
*
* End of SGQRTS
*
END
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