174 lines
4.0 KiB
Fortran
174 lines
4.0 KiB
Fortran
*> \brief \b SQRT13
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*
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* =========== DOCUMENTATION ===========
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*
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* Online html documentation available at
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* http://www.netlib.org/lapack/explore-html/
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*
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* Definition:
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* ===========
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*
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* SUBROUTINE SQRT13( SCALE, M, N, A, LDA, NORMA, ISEED )
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*
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* .. Scalar Arguments ..
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* INTEGER LDA, M, N, SCALE
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* REAL NORMA
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* ..
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* .. Array Arguments ..
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* INTEGER ISEED( 4 )
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* REAL A( LDA, * )
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* ..
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*
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*
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*> \par Purpose:
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* =============
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*>
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*> \verbatim
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*>
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*> SQRT13 generates a full-rank matrix that may be scaled to have large
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*> or small norm.
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*> \endverbatim
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*
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* Arguments:
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* ==========
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*
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*> \param[in] SCALE
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*> \verbatim
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*> SCALE is INTEGER
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*> SCALE = 1: normally scaled matrix
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*> SCALE = 2: matrix scaled up
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*> SCALE = 3: matrix scaled down
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*> \endverbatim
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*>
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*> \param[in] M
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*> \verbatim
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*> M is INTEGER
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*> The number of rows of the matrix A.
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*> \endverbatim
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*>
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*> \param[in] N
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*> \verbatim
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*> N is INTEGER
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*> The number of columns of A.
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*> \endverbatim
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*>
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*> \param[out] A
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*> \verbatim
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*> A is REAL array, dimension (LDA,N)
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*> The M-by-N matrix A.
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*> \endverbatim
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*>
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*> \param[in] LDA
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*> \verbatim
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*> LDA is INTEGER
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*> The leading dimension of the array A.
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*> \endverbatim
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*>
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*> \param[out] NORMA
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*> \verbatim
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*> NORMA is REAL
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*> The one-norm of A.
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*> \endverbatim
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*>
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*> \param[in,out] ISEED
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*> \verbatim
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*> ISEED is integer array, dimension (4)
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*> Seed for random number generator
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*> \endverbatim
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*
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* Authors:
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* ========
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*
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*> \author Univ. of Tennessee
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*> \author Univ. of California Berkeley
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*> \author Univ. of Colorado Denver
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*> \author NAG Ltd.
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*
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*> \ingroup single_lin
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*
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* =====================================================================
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SUBROUTINE SQRT13( SCALE, M, N, A, LDA, NORMA, ISEED )
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*
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* -- LAPACK test routine --
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* -- LAPACK is a software package provided by Univ. of Tennessee, --
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* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
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*
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* .. Scalar Arguments ..
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INTEGER LDA, M, N, SCALE
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REAL NORMA
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* ..
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* .. Array Arguments ..
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INTEGER ISEED( 4 )
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REAL A( LDA, * )
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* ..
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*
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* =====================================================================
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*
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* .. Parameters ..
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REAL ONE
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PARAMETER ( ONE = 1.0E0 )
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* ..
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* .. Local Scalars ..
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INTEGER INFO, J
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REAL BIGNUM, SMLNUM
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* ..
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* .. External Functions ..
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REAL SASUM, SLAMCH, SLANGE
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EXTERNAL SASUM, SLAMCH, SLANGE
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* ..
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* .. External Subroutines ..
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EXTERNAL SLABAD, SLARNV, SLASCL
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* ..
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* .. Intrinsic Functions ..
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INTRINSIC SIGN
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* ..
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* .. Local Arrays ..
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REAL DUMMY( 1 )
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* ..
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* .. Executable Statements ..
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*
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IF( M.LE.0 .OR. N.LE.0 )
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$ RETURN
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*
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* benign matrix
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*
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DO 10 J = 1, N
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CALL SLARNV( 2, ISEED, M, A( 1, J ) )
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IF( J.LE.M ) THEN
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A( J, J ) = A( J, J ) + SIGN( SASUM( M, A( 1, J ), 1 ),
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$ A( J, J ) )
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END IF
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10 CONTINUE
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*
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* scaled versions
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*
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IF( SCALE.NE.1 ) THEN
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NORMA = SLANGE( 'Max', M, N, A, LDA, DUMMY )
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SMLNUM = SLAMCH( 'Safe minimum' )
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BIGNUM = ONE / SMLNUM
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CALL SLABAD( SMLNUM, BIGNUM )
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SMLNUM = SMLNUM / SLAMCH( 'Epsilon' )
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BIGNUM = ONE / SMLNUM
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*
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IF( SCALE.EQ.2 ) THEN
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*
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* matrix scaled up
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*
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CALL SLASCL( 'General', 0, 0, NORMA, BIGNUM, M, N, A, LDA,
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$ INFO )
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ELSE IF( SCALE.EQ.3 ) THEN
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*
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* matrix scaled down
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*
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CALL SLASCL( 'General', 0, 0, NORMA, SMLNUM, M, N, A, LDA,
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$ INFO )
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END IF
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END IF
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*
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NORMA = SLANGE( 'One-norm', M, N, A, LDA, DUMMY )
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RETURN
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*
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* End of SQRT13
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*
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END
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