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lapack/TESTING/LIN/clatsy.f
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NAKATA Maho c537b6b5d3 TESTING/LIN: use LSAME for UPLO checks in latsp and latsy 
Replace direct UPLO character comparisons in the LATSP and LATSY test helpers with LSAME. This keeps option handling consistent with the LAPACK convention for case-insensitive checks.
2026-04-14 08:24:10 +09:00

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*> \brief \b CLATSY
*
* =========== DOCUMENTATION ===========
*
* Online html documentation available at
* http://www.netlib.org/lapack/explore-html/
*
* Definition:
* ===========
*
* SUBROUTINE CLATSY( UPLO, N, X, LDX, ISEED )
*
* .. Scalar Arguments ..
* CHARACTER UPLO
* INTEGER LDX, N
* ..
* .. Array Arguments ..
* INTEGER ISEED( 4 )
* COMPLEX X( LDX, * )
* ..
*
*
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> CLATSY generates a special test matrix for the complex symmetric
*> (indefinite) factorization. The pivot blocks of the generated matrix
*> will be in the following order:
*> 2x2 pivot block, non diagonalizable
*> 1x1 pivot block
*> 2x2 pivot block, diagonalizable
*> (cycle repeats)
*> A row interchange is required for each non-diagonalizable 2x2 block.
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in] UPLO
*> \verbatim
*> UPLO is CHARACTER
*> Specifies whether the generated matrix is to be upper or
*> lower triangular.
*> = 'U': Upper triangular
*> = 'L': Lower triangular
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*> N is INTEGER
*> The dimension of the matrix to be generated.
*> \endverbatim
*>
*> \param[out] X
*> \verbatim
*> X is COMPLEX array, dimension (LDX,N)
*> The generated matrix, consisting of 3x3 and 2x2 diagonal
*> blocks which result in the pivot sequence given above.
*> The matrix outside of these diagonal blocks is zero.
*> \endverbatim
*>
*> \param[in] LDX
*> \verbatim
*> LDX is INTEGER
*> The leading dimension of the array X.
*> \endverbatim
*>
*> \param[in,out] ISEED
*> \verbatim
*> ISEED is INTEGER array, dimension (4)
*> On entry, the seed for the random number generator. The last
*> of the four integers must be odd. (modified on exit)
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \ingroup complex_lin
*
* =====================================================================
SUBROUTINE CLATSY( UPLO, N, X, LDX, ISEED )
IMPLICIT NONE
*
* -- 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 ..
CHARACTER UPLO
INTEGER LDX, N
* ..
* .. Array Arguments ..
INTEGER ISEED( 4 )
COMPLEX X( LDX, * )
* ..
*
* =====================================================================
*
* .. Parameters ..
COMPLEX EYE
PARAMETER ( EYE = ( 0.0, 1.0 ) )
* ..
* .. Local Scalars ..
INTEGER I, J, N5
REAL ALPHA, ALPHA3, BETA
COMPLEX A, B, C, R
* ..
* .. External Functions ..
COMPLEX CLARND
LOGICAL LSAME
EXTERNAL CLARND, LSAME
* ..
* .. Intrinsic Functions ..
INTRINSIC ABS, SQRT
* ..
* .. Executable Statements ..
*
* Initialize constants
*
ALPHA = ( 1.+SQRT( 17. ) ) / 8.
BETA = ALPHA - 1. / 1000.
ALPHA3 = ALPHA*ALPHA*ALPHA
*
* UPLO = 'U': Upper triangular storage
*
IF( LSAME( UPLO, 'U' ) ) THEN
*
* Fill the upper triangle of the matrix with zeros.
*
DO 20 J = 1, N
DO 10 I = 1, J
X( I, J ) = 0.0
10 CONTINUE
20 CONTINUE
N5 = N / 5
N5 = N - 5*N5 + 1
*
DO 30 I = N, N5, -5
A = ALPHA3*CLARND( 5, ISEED )
B = CLARND( 5, ISEED ) / ALPHA
C = A - 2.*B*EYE
R = C / BETA
X( I, I ) = A
X( I-2, I ) = B
X( I-2, I-1 ) = R
X( I-2, I-2 ) = C
X( I-1, I-1 ) = CLARND( 2, ISEED )
X( I-3, I-3 ) = CLARND( 2, ISEED )
X( I-4, I-4 ) = CLARND( 2, ISEED )
IF( ABS( X( I-3, I-3 ) ).GT.ABS( X( I-4, I-4 ) ) ) THEN
X( I-4, I-3 ) = 2.0*X( I-3, I-3 )
ELSE
X( I-4, I-3 ) = 2.0*X( I-4, I-4 )
END IF
30 CONTINUE
*
* Clean-up for N not a multiple of 5.
*
I = N5 - 1
IF( I.GT.2 ) THEN
A = ALPHA3*CLARND( 5, ISEED )
B = CLARND( 5, ISEED ) / ALPHA
C = A - 2.*B*EYE
R = C / BETA
X( I, I ) = A
X( I-2, I ) = B
X( I-2, I-1 ) = R
X( I-2, I-2 ) = C
X( I-1, I-1 ) = CLARND( 2, ISEED )
I = I - 3
END IF
IF( I.GT.1 ) THEN
X( I, I ) = CLARND( 2, ISEED )
X( I-1, I-1 ) = CLARND( 2, ISEED )
IF( ABS( X( I, I ) ).GT.ABS( X( I-1, I-1 ) ) ) THEN
X( I-1, I ) = 2.0*X( I, I )
ELSE
X( I-1, I ) = 2.0*X( I-1, I-1 )
END IF
I = I - 2
ELSE IF( I.EQ.1 ) THEN
X( I, I ) = CLARND( 2, ISEED )
I = I - 1
END IF
*
* UPLO = 'L': Lower triangular storage
*
ELSE
*
* Fill the lower triangle of the matrix with zeros.
*
DO 50 J = 1, N
DO 40 I = J, N
X( I, J ) = 0.0
40 CONTINUE
50 CONTINUE
N5 = N / 5
N5 = N5*5
*
DO 60 I = 1, N5, 5
A = ALPHA3*CLARND( 5, ISEED )
B = CLARND( 5, ISEED ) / ALPHA
C = A - 2.*B*EYE
R = C / BETA
X( I, I ) = A
X( I+2, I ) = B
X( I+2, I+1 ) = R
X( I+2, I+2 ) = C
X( I+1, I+1 ) = CLARND( 2, ISEED )
X( I+3, I+3 ) = CLARND( 2, ISEED )
X( I+4, I+4 ) = CLARND( 2, ISEED )
IF( ABS( X( I+3, I+3 ) ).GT.ABS( X( I+4, I+4 ) ) ) THEN
X( I+4, I+3 ) = 2.0*X( I+3, I+3 )
ELSE
X( I+4, I+3 ) = 2.0*X( I+4, I+4 )
END IF
60 CONTINUE
*
* Clean-up for N not a multiple of 5.
*
I = N5 + 1
IF( I.LT.N-1 ) THEN
A = ALPHA3*CLARND( 5, ISEED )
B = CLARND( 5, ISEED ) / ALPHA
C = A - 2.*B*EYE
R = C / BETA
X( I, I ) = A
X( I+2, I ) = B
X( I+2, I+1 ) = R
X( I+2, I+2 ) = C
X( I+1, I+1 ) = CLARND( 2, ISEED )
I = I + 3
END IF
IF( I.LT.N ) THEN
X( I, I ) = CLARND( 2, ISEED )
X( I+1, I+1 ) = CLARND( 2, ISEED )
IF( ABS( X( I, I ) ).GT.ABS( X( I+1, I+1 ) ) ) THEN
X( I+1, I ) = 2.0*X( I, I )
ELSE
X( I+1, I ) = 2.0*X( I+1, I+1 )
END IF
I = I + 2
ELSE IF( I.EQ.N ) THEN
X( I, I ) = CLARND( 2, ISEED )
I = I + 1
END IF
END IF
*
RETURN
*
* End of CLATSY
*
END
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