711 lines
22 KiB
Fortran
711 lines
22 KiB
Fortran
*> \brief \b DLATME
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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 DLATME( N, DIST, ISEED, D, MODE, COND, DMAX, EI,
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* RSIGN,
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* UPPER, SIM, DS, MODES, CONDS, KL, KU, ANORM,
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* A,
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* LDA, WORK, INFO )
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*
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* .. Scalar Arguments ..
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* CHARACTER DIST, RSIGN, SIM, UPPER
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* INTEGER INFO, KL, KU, LDA, MODE, MODES, N
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* DOUBLE PRECISION ANORM, COND, CONDS, DMAX
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* ..
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* .. Array Arguments ..
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* CHARACTER EI( * )
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* INTEGER ISEED( 4 )
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* DOUBLE PRECISION A( LDA, * ), D( * ), DS( * ), WORK( * )
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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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*> DLATME generates random non-symmetric square matrices with
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*> specified eigenvalues for testing LAPACK programs.
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*>
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*> DLATME operates by applying the following sequence of
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*> operations:
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*>
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*> 1. Set the diagonal to D, where D may be input or
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*> computed according to MODE, COND, DMAX, and RSIGN
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*> as described below.
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*>
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*> 2. If complex conjugate pairs are desired (MODE=0 and EI(1)='R',
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*> or MODE=5), certain pairs of adjacent elements of D are
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*> interpreted as the real and complex parts of a complex
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*> conjugate pair; A thus becomes block diagonal, with 1x1
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*> and 2x2 blocks.
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*>
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*> 3. If UPPER='T', the upper triangle of A is set to random values
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*> out of distribution DIST.
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*>
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*> 4. If SIM='T', A is multiplied on the left by a random matrix
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*> X, whose singular values are specified by DS, MODES, and
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*> CONDS, and on the right by X inverse.
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*>
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*> 5. If KL < N-1, the lower bandwidth is reduced to KL using
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*> Householder transformations. If KU < N-1, the upper
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*> bandwidth is reduced to KU.
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*>
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*> 6. If ANORM is not negative, the matrix is scaled to have
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*> maximum-element-norm ANORM.
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*>
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*> (Note: since the matrix cannot be reduced beyond Hessenberg form,
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*> no packing options are available.)
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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] N
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*> \verbatim
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*> N is INTEGER
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*> The number of columns (or rows) of A. Not modified.
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*> \endverbatim
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*>
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*> \param[in] DIST
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*> \verbatim
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*> DIST is CHARACTER*1
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*> On entry, DIST specifies the type of distribution to be used
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*> to generate the random eigen-/singular values, and for the
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*> upper triangle (see UPPER).
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*> 'U' => UNIFORM( 0, 1 ) ( 'U' for uniform )
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*> 'S' => UNIFORM( -1, 1 ) ( 'S' for symmetric )
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*> 'N' => NORMAL( 0, 1 ) ( 'N' for normal )
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*> Not modified.
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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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*> On entry ISEED specifies the seed of the random number
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*> generator. They should lie between 0 and 4095 inclusive,
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*> and ISEED(4) should be odd. The random number generator
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*> uses a linear congruential sequence limited to small
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*> integers, and so should produce machine independent
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*> random numbers. The values of ISEED are changed on
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*> exit, and can be used in the next call to DLATME
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*> to continue the same random number sequence.
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*> Changed on exit.
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*> \endverbatim
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*>
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*> \param[in,out] D
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*> \verbatim
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*> D is DOUBLE PRECISION array, dimension ( N )
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*> This array is used to specify the eigenvalues of A. If
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*> MODE=0, then D is assumed to contain the eigenvalues (but
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*> see the description of EI), otherwise they will be
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*> computed according to MODE, COND, DMAX, and RSIGN and
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*> placed in D.
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*> Modified if MODE is nonzero.
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*> \endverbatim
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*>
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*> \param[in] MODE
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*> \verbatim
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*> MODE is INTEGER
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*> On entry this describes how the eigenvalues are to
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*> be specified:
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*> MODE = 0 means use D (with EI) as input
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*> MODE = 1 sets D(1)=1 and D(2:N)=1.0/COND
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*> MODE = 2 sets D(1:N-1)=1 and D(N)=1.0/COND
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*> MODE = 3 sets D(I)=COND**(-(I-1)/(N-1))
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*> MODE = 4 sets D(i)=1 - (i-1)/(N-1)*(1 - 1/COND)
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*> MODE = 5 sets D to random numbers in the range
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*> ( 1/COND , 1 ) such that their logarithms
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*> are uniformly distributed. Each odd-even pair
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*> of elements will be either used as two real
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*> eigenvalues or as the real and imaginary part
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*> of a complex conjugate pair of eigenvalues;
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*> the choice of which is done is random, with
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*> 50-50 probability, for each pair.
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*> MODE = 6 set D to random numbers from same distribution
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*> as the rest of the matrix.
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*> MODE < 0 has the same meaning as ABS(MODE), except that
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*> the order of the elements of D is reversed.
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*> Thus if MODE is between 1 and 4, D has entries ranging
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*> from 1 to 1/COND, if between -1 and -4, D has entries
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*> ranging from 1/COND to 1,
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*> Not modified.
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*> \endverbatim
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*>
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*> \param[in] COND
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*> \verbatim
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*> COND is DOUBLE PRECISION
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*> On entry, this is used as described under MODE above.
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*> If used, it must be >= 1. Not modified.
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*> \endverbatim
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*>
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*> \param[in] DMAX
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*> \verbatim
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*> DMAX is DOUBLE PRECISION
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*> If MODE is neither -6, 0 nor 6, the contents of D, as
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*> computed according to MODE and COND, will be scaled by
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*> DMAX / max(abs(D(i))). Note that DMAX need not be
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*> positive: if DMAX is negative (or zero), D will be
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*> scaled by a negative number (or zero).
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*> Not modified.
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*> \endverbatim
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*>
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*> \param[in] EI
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*> \verbatim
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*> EI is CHARACTER*1 array, dimension ( N )
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*> If MODE is 0, and EI(1) is not ' ' (space character),
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*> this array specifies which elements of D (on input) are
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*> real eigenvalues and which are the real and imaginary parts
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*> of a complex conjugate pair of eigenvalues. The elements
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*> of EI may then only have the values 'R' and 'I'. If
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*> EI(j)='R' and EI(j+1)='I', then the j-th eigenvalue is
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*> CMPLX( D(j) , D(j+1) ), and the (j+1)-th is the complex
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*> conjugate thereof. If EI(j)=EI(j+1)='R', then the j-th
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*> eigenvalue is D(j) (i.e., real). EI(1) may not be 'I',
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*> nor may two adjacent elements of EI both have the value 'I'.
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*> If MODE is not 0, then EI is ignored. If MODE is 0 and
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*> EI(1)=' ', then the eigenvalues will all be real.
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*> Not modified.
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*> \endverbatim
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*>
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*> \param[in] RSIGN
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*> \verbatim
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*> RSIGN is CHARACTER*1
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*> If MODE is not 0, 6, or -6, and RSIGN='T', then the
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*> elements of D, as computed according to MODE and COND, will
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*> be multiplied by a random sign (+1 or -1). If RSIGN='F',
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*> they will not be. RSIGN may only have the values 'T' or
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*> 'F'.
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*> Not modified.
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*> \endverbatim
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*>
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*> \param[in] UPPER
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*> \verbatim
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*> UPPER is CHARACTER*1
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*> If UPPER='T', then the elements of A above the diagonal
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*> (and above the 2x2 diagonal blocks, if A has complex
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*> eigenvalues) will be set to random numbers out of DIST.
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*> If UPPER='F', they will not. UPPER may only have the
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*> values 'T' or 'F'.
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*> Not modified.
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*> \endverbatim
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*>
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*> \param[in] SIM
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*> \verbatim
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*> SIM is CHARACTER*1
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*> If SIM='T', then A will be operated on by a "similarity
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*> transform", i.e., multiplied on the left by a matrix X and
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*> on the right by X inverse. X = U S V, where U and V are
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*> random unitary matrices and S is a (diagonal) matrix of
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*> singular values specified by DS, MODES, and CONDS. If
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*> SIM='F', then A will not be transformed.
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*> Not modified.
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*> \endverbatim
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*>
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*> \param[in,out] DS
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*> \verbatim
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*> DS is DOUBLE PRECISION array, dimension ( N )
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*> This array is used to specify the singular values of X,
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*> in the same way that D specifies the eigenvalues of A.
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*> If MODE=0, the DS contains the singular values, which
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*> may not be zero.
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*> Modified if MODE is nonzero.
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*> \endverbatim
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*>
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*> \param[in] MODES
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*> \verbatim
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*> MODES is INTEGER
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*> \endverbatim
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*>
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*> \param[in] CONDS
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*> \verbatim
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*> CONDS is DOUBLE PRECISION
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*> Same as MODE and COND, but for specifying the diagonal
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*> of S. MODES=-6 and +6 are not allowed (since they would
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*> result in randomly ill-conditioned eigenvalues.)
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*> \endverbatim
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*>
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*> \param[in] KL
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*> \verbatim
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*> KL is INTEGER
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*> This specifies the lower bandwidth of the matrix. KL=1
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*> specifies upper Hessenberg form. If KL is at least N-1,
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*> then A will have full lower bandwidth. KL must be at
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*> least 1.
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*> Not modified.
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*> \endverbatim
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*>
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*> \param[in] KU
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*> \verbatim
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*> KU is INTEGER
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*> This specifies the upper bandwidth of the matrix. KU=1
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*> specifies lower Hessenberg form. If KU is at least N-1,
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*> then A will have full upper bandwidth; if KU and KL
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*> are both at least N-1, then A will be dense. Only one of
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*> KU and KL may be less than N-1. KU must be at least 1.
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*> Not modified.
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*> \endverbatim
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*>
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*> \param[in] ANORM
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*> \verbatim
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*> ANORM is DOUBLE PRECISION
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*> If ANORM is not negative, then A will be scaled by a non-
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*> negative real number to make the maximum-element-norm of A
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*> to be ANORM.
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*> Not modified.
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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 DOUBLE PRECISION array, dimension ( LDA, N )
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*> On exit A is the desired test matrix.
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*> Modified.
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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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*> LDA specifies the first dimension of A as declared in the
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*> calling program. LDA must be at least N.
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*> Not modified.
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*> \endverbatim
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*>
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*> \param[out] WORK
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*> \verbatim
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*> WORK is DOUBLE PRECISION array, dimension ( 3*N )
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*> Workspace.
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*> Modified.
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*> \endverbatim
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*>
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*> \param[out] INFO
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*> \verbatim
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*> INFO is INTEGER
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*> Error code. On exit, INFO will be set to one of the
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*> following values:
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*> 0 => normal return
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*> -1 => N negative
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*> -2 => DIST illegal string
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*> -5 => MODE not in range -6 to 6
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*> -6 => COND less than 1.0, and MODE neither -6, 0 nor 6
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*> -8 => EI(1) is not ' ' or 'R', EI(j) is not 'R' or 'I', or
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*> two adjacent elements of EI are 'I'.
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*> -9 => RSIGN is not 'T' or 'F'
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*> -10 => UPPER is not 'T' or 'F'
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*> -11 => SIM is not 'T' or 'F'
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*> -12 => MODES=0 and DS has a zero singular value.
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*> -13 => MODES is not in the range -5 to 5.
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*> -14 => MODES is nonzero and CONDS is less than 1.
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*> -15 => KL is less than 1.
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*> -16 => KU is less than 1, or KL and KU are both less than
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*> N-1.
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*> -19 => LDA is less than N.
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*> 1 => Error return from DLATM1 (computing D)
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*> 2 => Cannot scale to DMAX (max. eigenvalue is 0)
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*> 3 => Error return from DLATM1 (computing DS)
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*> 4 => Error return from DLARGE
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*> 5 => Zero singular value from DLATM1.
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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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*> \date November 2011
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*
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*> \ingroup double_matgen
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*
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* =====================================================================
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SUBROUTINE DLATME( N, DIST, ISEED, D, MODE, COND, DMAX, EI,
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$ RSIGN,
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$ UPPER, SIM, DS, MODES, CONDS, KL, KU, ANORM,
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$ A,
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$ LDA, WORK, INFO )
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*
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* -- LAPACK computational routine (version 3.4.0) --
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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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* November 2011
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*
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* .. Scalar Arguments ..
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CHARACTER DIST, RSIGN, SIM, UPPER
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INTEGER INFO, KL, KU, LDA, MODE, MODES, N
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DOUBLE PRECISION ANORM, COND, CONDS, DMAX
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* ..
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* .. Array Arguments ..
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CHARACTER EI( * )
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INTEGER ISEED( 4 )
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DOUBLE PRECISION A( LDA, * ), D( * ), DS( * ), WORK( * )
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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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DOUBLE PRECISION ZERO
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PARAMETER ( ZERO = 0.0D0 )
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DOUBLE PRECISION ONE
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PARAMETER ( ONE = 1.0D0 )
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DOUBLE PRECISION HALF
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PARAMETER ( HALF = 1.0D0 / 2.0D0 )
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* ..
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* .. Local Scalars ..
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LOGICAL BADEI, BADS, USEEI
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INTEGER I, IC, ICOLS, IDIST, IINFO, IR, IROWS, IRSIGN,
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$ ISIM, IUPPER, J, JC, JCR, JR
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DOUBLE PRECISION ALPHA, TAU, TEMP, XNORMS
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* ..
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* .. Local Arrays ..
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DOUBLE PRECISION TEMPA( 1 )
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* ..
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* .. External Functions ..
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LOGICAL LSAME
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DOUBLE PRECISION DLANGE, DLARAN
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EXTERNAL LSAME, DLANGE, DLARAN
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* ..
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* .. External Subroutines ..
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EXTERNAL DCOPY, DGEMV, DGER, DLARFG, DLARGE, DLARNV,
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$ DLASET, DLATM1, DSCAL, XERBLA
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* ..
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* .. Intrinsic Functions ..
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INTRINSIC ABS, MAX, MOD
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* ..
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* .. Executable Statements ..
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*
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* 1) Decode and Test the input parameters.
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* Initialize flags & seed.
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*
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INFO = 0
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*
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* Quick return if possible
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*
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IF( N.EQ.0 )
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$ RETURN
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*
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* Decode DIST
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*
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IF( LSAME( DIST, 'U' ) ) THEN
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IDIST = 1
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ELSE IF( LSAME( DIST, 'S' ) ) THEN
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IDIST = 2
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ELSE IF( LSAME( DIST, 'N' ) ) THEN
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IDIST = 3
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ELSE
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IDIST = -1
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END IF
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*
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* Check EI
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*
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USEEI = .TRUE.
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BADEI = .FALSE.
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IF( LSAME( EI( 1 ), ' ' ) .OR. MODE.NE.0 ) THEN
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USEEI = .FALSE.
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ELSE
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IF( LSAME( EI( 1 ), 'R' ) ) THEN
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DO 10 J = 2, N
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IF( LSAME( EI( J ), 'I' ) ) THEN
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IF( LSAME( EI( J-1 ), 'I' ) )
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$ BADEI = .TRUE.
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ELSE
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IF( .NOT.LSAME( EI( J ), 'R' ) )
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$ BADEI = .TRUE.
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END IF
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10 CONTINUE
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ELSE
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BADEI = .TRUE.
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END IF
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END IF
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*
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* Decode RSIGN
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*
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IF( LSAME( RSIGN, 'T' ) ) THEN
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IRSIGN = 1
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ELSE IF( LSAME( RSIGN, 'F' ) ) THEN
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IRSIGN = 0
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ELSE
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IRSIGN = -1
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END IF
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*
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* Decode UPPER
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*
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IF( LSAME( UPPER, 'T' ) ) THEN
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IUPPER = 1
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ELSE IF( LSAME( UPPER, 'F' ) ) THEN
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IUPPER = 0
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ELSE
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IUPPER = -1
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END IF
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*
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* Decode SIM
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*
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IF( LSAME( SIM, 'T' ) ) THEN
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ISIM = 1
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ELSE IF( LSAME( SIM, 'F' ) ) THEN
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ISIM = 0
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ELSE
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ISIM = -1
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END IF
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*
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* Check DS, if MODES=0 and ISIM=1
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*
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BADS = .FALSE.
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IF( MODES.EQ.0 .AND. ISIM.EQ.1 ) THEN
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DO 20 J = 1, N
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IF( DS( J ).EQ.ZERO )
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$ BADS = .TRUE.
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20 CONTINUE
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END IF
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*
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* Set INFO if an error
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*
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IF( N.LT.0 ) THEN
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INFO = -1
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ELSE IF( IDIST.EQ.-1 ) THEN
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INFO = -2
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ELSE IF( ABS( MODE ).GT.6 ) THEN
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INFO = -5
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ELSE IF( ( MODE.NE.0 .AND. ABS( MODE ).NE.6 ) .AND. COND.LT.ONE )
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$ THEN
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INFO = -6
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ELSE IF( BADEI ) THEN
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INFO = -8
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ELSE IF( IRSIGN.EQ.-1 ) THEN
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INFO = -9
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ELSE IF( IUPPER.EQ.-1 ) THEN
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INFO = -10
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ELSE IF( ISIM.EQ.-1 ) THEN
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INFO = -11
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ELSE IF( BADS ) THEN
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INFO = -12
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ELSE IF( ISIM.EQ.1 .AND. ABS( MODES ).GT.5 ) THEN
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INFO = -13
|
|
ELSE IF( ISIM.EQ.1 .AND. MODES.NE.0 .AND. CONDS.LT.ONE ) THEN
|
|
INFO = -14
|
|
ELSE IF( KL.LT.1 ) THEN
|
|
INFO = -15
|
|
ELSE IF( KU.LT.1 .OR. ( KU.LT.N-1 .AND. KL.LT.N-1 ) ) THEN
|
|
INFO = -16
|
|
ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
|
|
INFO = -19
|
|
END IF
|
|
*
|
|
IF( INFO.NE.0 ) THEN
|
|
CALL XERBLA( 'DLATME', -INFO )
|
|
RETURN
|
|
END IF
|
|
*
|
|
* Initialize random number generator
|
|
*
|
|
DO 30 I = 1, 4
|
|
ISEED( I ) = MOD( ABS( ISEED( I ) ), 4096 )
|
|
30 CONTINUE
|
|
*
|
|
IF( MOD( ISEED( 4 ), 2 ).NE.1 )
|
|
$ ISEED( 4 ) = ISEED( 4 ) + 1
|
|
*
|
|
* 2) Set up diagonal of A
|
|
*
|
|
* Compute D according to COND and MODE
|
|
*
|
|
CALL DLATM1( MODE, COND, IRSIGN, IDIST, ISEED, D, N, IINFO )
|
|
IF( IINFO.NE.0 ) THEN
|
|
INFO = 1
|
|
RETURN
|
|
END IF
|
|
IF( MODE.NE.0 .AND. ABS( MODE ).NE.6 ) THEN
|
|
*
|
|
* Scale by DMAX
|
|
*
|
|
TEMP = ABS( D( 1 ) )
|
|
DO 40 I = 2, N
|
|
TEMP = MAX( TEMP, ABS( D( I ) ) )
|
|
40 CONTINUE
|
|
*
|
|
IF( TEMP.GT.ZERO ) THEN
|
|
ALPHA = DMAX / TEMP
|
|
ELSE IF( DMAX.NE.ZERO ) THEN
|
|
INFO = 2
|
|
RETURN
|
|
ELSE
|
|
ALPHA = ZERO
|
|
END IF
|
|
*
|
|
CALL DSCAL( N, ALPHA, D, 1 )
|
|
*
|
|
END IF
|
|
*
|
|
CALL DLASET( 'Full', N, N, ZERO, ZERO, A, LDA )
|
|
CALL DCOPY( N, D, 1, A, LDA+1 )
|
|
*
|
|
* Set up complex conjugate pairs
|
|
*
|
|
IF( MODE.EQ.0 ) THEN
|
|
IF( USEEI ) THEN
|
|
DO 50 J = 2, N
|
|
IF( LSAME( EI( J ), 'I' ) ) THEN
|
|
A( J-1, J ) = A( J, J )
|
|
A( J, J-1 ) = -A( J, J )
|
|
A( J, J ) = A( J-1, J-1 )
|
|
END IF
|
|
50 CONTINUE
|
|
END IF
|
|
*
|
|
ELSE IF( ABS( MODE ).EQ.5 ) THEN
|
|
*
|
|
DO 60 J = 2, N, 2
|
|
IF( DLARAN( ISEED ).GT.HALF ) THEN
|
|
A( J-1, J ) = A( J, J )
|
|
A( J, J-1 ) = -A( J, J )
|
|
A( J, J ) = A( J-1, J-1 )
|
|
END IF
|
|
60 CONTINUE
|
|
END IF
|
|
*
|
|
* 3) If UPPER='T', set upper triangle of A to random numbers.
|
|
* (but don't modify the corners of 2x2 blocks.)
|
|
*
|
|
IF( IUPPER.NE.0 ) THEN
|
|
DO 70 JC = 2, N
|
|
IF( A( JC-1, JC ).NE.ZERO ) THEN
|
|
JR = JC - 2
|
|
ELSE
|
|
JR = JC - 1
|
|
END IF
|
|
CALL DLARNV( IDIST, ISEED, JR, A( 1, JC ) )
|
|
70 CONTINUE
|
|
END IF
|
|
*
|
|
* 4) If SIM='T', apply similarity transformation.
|
|
*
|
|
* -1
|
|
* Transform is X A X , where X = U S V, thus
|
|
*
|
|
* it is U S V A V' (1/S) U'
|
|
*
|
|
IF( ISIM.NE.0 ) THEN
|
|
*
|
|
* Compute S (singular values of the eigenvector matrix)
|
|
* according to CONDS and MODES
|
|
*
|
|
CALL DLATM1( MODES, CONDS, 0, 0, ISEED, DS, N, IINFO )
|
|
IF( IINFO.NE.0 ) THEN
|
|
INFO = 3
|
|
RETURN
|
|
END IF
|
|
*
|
|
* Multiply by V and V'
|
|
*
|
|
CALL DLARGE( N, A, LDA, ISEED, WORK, IINFO )
|
|
IF( IINFO.NE.0 ) THEN
|
|
INFO = 4
|
|
RETURN
|
|
END IF
|
|
*
|
|
* Multiply by S and (1/S)
|
|
*
|
|
DO 80 J = 1, N
|
|
CALL DSCAL( N, DS( J ), A( J, 1 ), LDA )
|
|
IF( DS( J ).NE.ZERO ) THEN
|
|
CALL DSCAL( N, ONE / DS( J ), A( 1, J ), 1 )
|
|
ELSE
|
|
INFO = 5
|
|
RETURN
|
|
END IF
|
|
80 CONTINUE
|
|
*
|
|
* Multiply by U and U'
|
|
*
|
|
CALL DLARGE( N, A, LDA, ISEED, WORK, IINFO )
|
|
IF( IINFO.NE.0 ) THEN
|
|
INFO = 4
|
|
RETURN
|
|
END IF
|
|
END IF
|
|
*
|
|
* 5) Reduce the bandwidth.
|
|
*
|
|
IF( KL.LT.N-1 ) THEN
|
|
*
|
|
* Reduce bandwidth -- kill column
|
|
*
|
|
DO 90 JCR = KL + 1, N - 1
|
|
IC = JCR - KL
|
|
IROWS = N + 1 - JCR
|
|
ICOLS = N + KL - JCR
|
|
*
|
|
CALL DCOPY( IROWS, A( JCR, IC ), 1, WORK, 1 )
|
|
XNORMS = WORK( 1 )
|
|
CALL DLARFG( IROWS, XNORMS, WORK( 2 ), 1, TAU )
|
|
WORK( 1 ) = ONE
|
|
*
|
|
CALL DGEMV( 'T', IROWS, ICOLS, ONE, A( JCR, IC+1 ), LDA,
|
|
$ WORK, 1, ZERO, WORK( IROWS+1 ), 1 )
|
|
CALL DGER( IROWS, ICOLS, -TAU, WORK, 1, WORK( IROWS+1 ), 1,
|
|
$ A( JCR, IC+1 ), LDA )
|
|
*
|
|
CALL DGEMV( 'N', N, IROWS, ONE, A( 1, JCR ), LDA, WORK, 1,
|
|
$ ZERO, WORK( IROWS+1 ), 1 )
|
|
CALL DGER( N, IROWS, -TAU, WORK( IROWS+1 ), 1, WORK, 1,
|
|
$ A( 1, JCR ), LDA )
|
|
*
|
|
A( JCR, IC ) = XNORMS
|
|
CALL DLASET( 'Full', IROWS-1, 1, ZERO, ZERO, A( JCR+1, IC ),
|
|
$ LDA )
|
|
90 CONTINUE
|
|
ELSE IF( KU.LT.N-1 ) THEN
|
|
*
|
|
* Reduce upper bandwidth -- kill a row at a time.
|
|
*
|
|
DO 100 JCR = KU + 1, N - 1
|
|
IR = JCR - KU
|
|
IROWS = N + KU - JCR
|
|
ICOLS = N + 1 - JCR
|
|
*
|
|
CALL DCOPY( ICOLS, A( IR, JCR ), LDA, WORK, 1 )
|
|
XNORMS = WORK( 1 )
|
|
CALL DLARFG( ICOLS, XNORMS, WORK( 2 ), 1, TAU )
|
|
WORK( 1 ) = ONE
|
|
*
|
|
CALL DGEMV( 'N', IROWS, ICOLS, ONE, A( IR+1, JCR ), LDA,
|
|
$ WORK, 1, ZERO, WORK( ICOLS+1 ), 1 )
|
|
CALL DGER( IROWS, ICOLS, -TAU, WORK( ICOLS+1 ), 1, WORK, 1,
|
|
$ A( IR+1, JCR ), LDA )
|
|
*
|
|
CALL DGEMV( 'C', ICOLS, N, ONE, A( JCR, 1 ), LDA, WORK, 1,
|
|
$ ZERO, WORK( ICOLS+1 ), 1 )
|
|
CALL DGER( ICOLS, N, -TAU, WORK, 1, WORK( ICOLS+1 ), 1,
|
|
$ A( JCR, 1 ), LDA )
|
|
*
|
|
A( IR, JCR ) = XNORMS
|
|
CALL DLASET( 'Full', 1, ICOLS-1, ZERO, ZERO, A( IR, JCR+1 ),
|
|
$ LDA )
|
|
100 CONTINUE
|
|
END IF
|
|
*
|
|
* Scale the matrix to have norm ANORM
|
|
*
|
|
IF( ANORM.GE.ZERO ) THEN
|
|
TEMP = DLANGE( 'M', N, N, A, LDA, TEMPA )
|
|
IF( TEMP.GT.ZERO ) THEN
|
|
ALPHA = ANORM / TEMP
|
|
DO 110 J = 1, N
|
|
CALL DSCAL( N, ALPHA, A( 1, J ), 1 )
|
|
110 CONTINUE
|
|
END IF
|
|
END IF
|
|
*
|
|
RETURN
|
|
*
|
|
* End of DLATME
|
|
*
|
|
END
|