dqrt13()

subroutine dqrt13	(	integer	SCALE,
		integer	M,
		integer	N,
		double precision, dimension( lda, * )	A,
		integer	LDA,
		double precision	NORMA,
		integer, dimension( 4 )	ISEED
	)

DQRT13

Purpose:

 DQRT13 generates a full-rank matrix that may be scaled to have large
 or small norm.

Parameters

[in]	SCALE	SCALE is INTEGER SCALE = 1: normally scaled matrix SCALE = 2: matrix scaled up SCALE = 3: matrix scaled down
[in]	M	M is INTEGER The number of rows of the matrix A.
[in]	N	N is INTEGER The number of columns of A.
[out]	A	A is DOUBLE PRECISION array, dimension (LDA,N) The M-by-N matrix A.
[in]	LDA	LDA is INTEGER The leading dimension of the array A.
[out]	NORMA	NORMA is DOUBLE PRECISION The one-norm of A.
[in,out]	ISEED	ISEED is integer array, dimension (4) Seed for random number generator

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 90 of file dqrt13.f.

*
*  -- 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, M, N, SCALE
      DOUBLE PRECISION   NORMA
*     ..
*     .. Array Arguments ..
      INTEGER            ISEED( 4 )
      DOUBLE PRECISION   A( LDA, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE
      parameter( one = 1.0d0 )
*     ..
*     .. Local Scalars ..
      INTEGER            INFO, J
      DOUBLE PRECISION   BIGNUM, SMLNUM
*     ..
*     .. External Functions ..
      DOUBLE PRECISION   DASUM, DLAMCH, DLANGE
      EXTERNAL           dasum, dlamch, dlange
*     ..
*     .. External Subroutines ..
      EXTERNAL           dlabad, dlarnv, dlascl
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          sign
*     ..
*     .. Local Arrays ..
      DOUBLE PRECISION   DUMMY( 1 )
*     ..
*     .. Executable Statements ..
*
      IF( m.LE.0 .OR. n.LE.0 )
     $   RETURN
*
*     benign matrix
*
      DO 10 j = 1, n
         CALL dlarnv( 2, iseed, m, a( 1, j ) )
         IF( j.LE.m ) THEN
            a( j, j ) = a( j, j ) + sign( dasum( m, a( 1, j ), 1 ),
     $                  a( j, j ) )
         END IF
   10 CONTINUE
*
*     scaled versions
*
      IF( scale.NE.1 ) THEN
         norma = dlange( 'Max', m, n, a, lda, dummy )
         smlnum = dlamch( 'Safe minimum' )
         bignum = one / smlnum
         CALL dlabad( smlnum, bignum )
         smlnum = smlnum / dlamch( 'Epsilon' )
         bignum = one / smlnum
*
         IF( scale.EQ.2 ) THEN
*
*           matrix scaled up
*
            CALL dlascl( 'General', 0, 0, norma, bignum, m, n, a, lda,
     $                   info )
         ELSE IF( scale.EQ.3 ) THEN
*
*           matrix scaled down
*
            CALL dlascl( 'General', 0, 0, norma, smlnum, m, n, a, lda,
     $                   info )
         END IF
      END IF
*
      norma = dlange( 'One-norm', m, n, a, lda, dummy )
      RETURN
*
*     End of DQRT13
*

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