numeric-linalg
Educational material on the SciPy implementation of numerical linear algebra algorithms
| Name | Size | Mode | |
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| lapack/TESTING/LIN/zlattb.f | 22537B | -rw-r--r-- |
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*> \brief \b ZLATTB * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * SUBROUTINE ZLATTB( IMAT, UPLO, TRANS, DIAG, ISEED, N, KD, AB, * LDAB, B, WORK, RWORK, INFO ) * * .. Scalar Arguments .. * CHARACTER DIAG, TRANS, UPLO * INTEGER IMAT, INFO, KD, LDAB, N * .. * .. Array Arguments .. * INTEGER ISEED( 4 ) * DOUBLE PRECISION RWORK( * ) * COMPLEX*16 AB( LDAB, * ), B( * ), WORK( * ) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> ZLATTB generates a triangular test matrix in 2-dimensional storage. *> IMAT and UPLO uniquely specify the properties of the test matrix, *> which is returned in the array A. *> \endverbatim * * Arguments: * ========== * *> \param[in] IMAT *> \verbatim *> IMAT is INTEGER *> An integer key describing which matrix to generate for this *> path. *> \endverbatim *> *> \param[in] UPLO *> \verbatim *> UPLO is CHARACTER*1 *> Specifies whether the matrix A will be upper or lower *> triangular. *> = 'U': Upper triangular *> = 'L': Lower triangular *> \endverbatim *> *> \param[in] TRANS *> \verbatim *> TRANS is CHARACTER*1 *> Specifies whether the matrix or its transpose will be used. *> = 'N': No transpose *> = 'T': Transpose *> = 'C': Conjugate transpose (= transpose) *> \endverbatim *> *> \param[out] DIAG *> \verbatim *> DIAG is CHARACTER*1 *> Specifies whether or not the matrix A is unit triangular. *> = 'N': Non-unit triangular *> = 'U': Unit triangular *> \endverbatim *> *> \param[in,out] ISEED *> \verbatim *> ISEED is INTEGER array, dimension (4) *> The seed vector for the random number generator (used in *> ZLATMS). Modified on exit. *> \endverbatim *> *> \param[in] N *> \verbatim *> N is INTEGER *> The order of the matrix to be generated. *> \endverbatim *> *> \param[in] KD *> \verbatim *> KD is INTEGER *> The number of superdiagonals or subdiagonals of the banded *> triangular matrix A. KD >= 0. *> \endverbatim *> *> \param[out] AB *> \verbatim *> AB is COMPLEX*16 array, dimension (LDAB,N) *> The upper or lower triangular banded matrix A, stored in the *> first KD+1 rows of AB. Let j be a column of A, 1<=j<=n. *> If UPLO = 'U', AB(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j. *> If UPLO = 'L', AB(1+i-j,j) = A(i,j) for j<=i<=min(n,j+kd). *> \endverbatim *> *> \param[in] LDAB *> \verbatim *> LDAB is INTEGER *> The leading dimension of the array AB. LDAB >= KD+1. *> \endverbatim *> *> \param[out] B *> \verbatim *> B is COMPLEX*16 array, dimension (N) *> \endverbatim *> *> \param[out] WORK *> \verbatim *> WORK is COMPLEX*16 array, dimension (2*N) *> \endverbatim *> *> \param[out] RWORK *> \verbatim *> RWORK is DOUBLE PRECISION array, dimension (N) *> \endverbatim *> *> \param[out] INFO *> \verbatim *> INFO is INTEGER *> = 0: successful exit *> < 0: if INFO = -i, the i-th argument had an illegal value *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup complex16_lin * * ===================================================================== SUBROUTINE ZLATTB( IMAT, UPLO, TRANS, DIAG, ISEED, N, KD, AB, $ LDAB, B, WORK, RWORK, INFO ) * * -- 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 DIAG, TRANS, UPLO INTEGER IMAT, INFO, KD, LDAB, N * .. * .. Array Arguments .. INTEGER ISEED( 4 ) DOUBLE PRECISION RWORK( * ) COMPLEX*16 AB( LDAB, * ), B( * ), WORK( * ) * .. * * ===================================================================== * * .. Parameters .. DOUBLE PRECISION ONE, TWO, ZERO PARAMETER ( ONE = 1.0D+0, TWO = 2.0D+0, ZERO = 0.0D+0 ) * .. * .. Local Scalars .. LOGICAL UPPER CHARACTER DIST, PACKIT, TYPE CHARACTER*3 PATH INTEGER I, IOFF, IY, J, JCOUNT, KL, KU, LENJ, MODE DOUBLE PRECISION ANORM, BIGNUM, BNORM, BSCAL, CNDNUM, REXP, $ SFAC, SMLNUM, TEXP, TLEFT, TNORM, TSCAL, ULP, $ UNFL COMPLEX*16 PLUS1, PLUS2, STAR1 * .. * .. External Functions .. LOGICAL LSAME INTEGER IZAMAX DOUBLE PRECISION DLAMCH, DLARND COMPLEX*16 ZLARND EXTERNAL LSAME, IZAMAX, DLAMCH, DLARND, ZLARND * .. * .. External Subroutines .. EXTERNAL DLARNV, ZCOPY, ZDSCAL, ZLARNV, ZLATB4, ZLATMS, $ ZSWAP * .. * .. Intrinsic Functions .. INTRINSIC ABS, DBLE, DCMPLX, MAX, MIN, SQRT * .. * .. Executable Statements .. * PATH( 1: 1 ) = 'Zomplex precision' PATH( 2: 3 ) = 'TB' UNFL = DLAMCH( 'Safe minimum' ) ULP = DLAMCH( 'Epsilon' )*DLAMCH( 'Base' ) SMLNUM = UNFL BIGNUM = ( ONE-ULP ) / SMLNUM IF( ( IMAT.GE.6 .AND. IMAT.LE.9 ) .OR. IMAT.EQ.17 ) THEN DIAG = 'U' ELSE DIAG = 'N' END IF INFO = 0 * * Quick return if N.LE.0. * IF( N.LE.0 ) $ RETURN * * Call ZLATB4 to set parameters for ZLATMS. * UPPER = LSAME( UPLO, 'U' ) IF( UPPER ) THEN CALL ZLATB4( PATH, IMAT, N, N, TYPE, KL, KU, ANORM, MODE, $ CNDNUM, DIST ) KU = KD IOFF = 1 + MAX( 0, KD-N+1 ) KL = 0 PACKIT = 'Q' ELSE CALL ZLATB4( PATH, -IMAT, N, N, TYPE, KL, KU, ANORM, MODE, $ CNDNUM, DIST ) KL = KD IOFF = 1 KU = 0 PACKIT = 'B' END IF * * IMAT <= 5: Non-unit triangular matrix * IF( IMAT.LE.5 ) THEN CALL ZLATMS( N, N, DIST, ISEED, TYPE, RWORK, MODE, CNDNUM, $ ANORM, KL, KU, PACKIT, AB( IOFF, 1 ), LDAB, WORK, $ INFO ) * * IMAT > 5: Unit triangular matrix * The diagonal is deliberately set to something other than 1. * * IMAT = 6: Matrix is the identity * ELSE IF( IMAT.EQ.6 ) THEN IF( UPPER ) THEN DO 20 J = 1, N DO 10 I = MAX( 1, KD+2-J ), KD AB( I, J ) = ZERO 10 CONTINUE AB( KD+1, J ) = J 20 CONTINUE ELSE DO 40 J = 1, N AB( 1, J ) = J DO 30 I = 2, MIN( KD+1, N-J+1 ) AB( I, J ) = ZERO 30 CONTINUE 40 CONTINUE END IF * * IMAT > 6: Non-trivial unit triangular matrix * * A unit triangular matrix T with condition CNDNUM is formed. * In this version, T only has bandwidth 2, the rest of it is zero. * ELSE IF( IMAT.LE.9 ) THEN TNORM = SQRT( CNDNUM ) * * Initialize AB to zero. * IF( UPPER ) THEN DO 60 J = 1, N DO 50 I = MAX( 1, KD+2-J ), KD AB( I, J ) = ZERO 50 CONTINUE AB( KD+1, J ) = DBLE( J ) 60 CONTINUE ELSE DO 80 J = 1, N DO 70 I = 2, MIN( KD+1, N-J+1 ) AB( I, J ) = ZERO 70 CONTINUE AB( 1, J ) = DBLE( J ) 80 CONTINUE END IF * * Special case: T is tridiagonal. Set every other offdiagonal * so that the matrix has norm TNORM+1. * IF( KD.EQ.1 ) THEN IF( UPPER ) THEN AB( 1, 2 ) = TNORM*ZLARND( 5, ISEED ) LENJ = ( N-3 ) / 2 CALL ZLARNV( 2, ISEED, LENJ, WORK ) DO 90 J = 1, LENJ AB( 1, 2*( J+1 ) ) = TNORM*WORK( J ) 90 CONTINUE ELSE AB( 2, 1 ) = TNORM*ZLARND( 5, ISEED ) LENJ = ( N-3 ) / 2 CALL ZLARNV( 2, ISEED, LENJ, WORK ) DO 100 J = 1, LENJ AB( 2, 2*J+1 ) = TNORM*WORK( J ) 100 CONTINUE END IF ELSE IF( KD.GT.1 ) THEN * * Form a unit triangular matrix T with condition CNDNUM. T is * given by * | 1 + * | * | 1 + | * T = | 1 + * | * | 1 + | * | 1 + * | * | 1 + | * | . . . | * Each element marked with a '*' is formed by taking the product * of the adjacent elements marked with '+'. The '*'s can be * chosen freely, and the '+'s are chosen so that the inverse of * T will have elements of the same magnitude as T. * * The two offdiagonals of T are stored in WORK. * STAR1 = TNORM*ZLARND( 5, ISEED ) SFAC = SQRT( TNORM ) PLUS1 = SFAC*ZLARND( 5, ISEED ) DO 110 J = 1, N, 2 PLUS2 = STAR1 / PLUS1 WORK( J ) = PLUS1 WORK( N+J ) = STAR1 IF( J+1.LE.N ) THEN WORK( J+1 ) = PLUS2 WORK( N+J+1 ) = ZERO PLUS1 = STAR1 / PLUS2 * * Generate a new *-value with norm between sqrt(TNORM) * and TNORM. * REXP = DLARND( 2, ISEED ) IF( REXP.LT.ZERO ) THEN STAR1 = -SFAC**( ONE-REXP )*ZLARND( 5, ISEED ) ELSE STAR1 = SFAC**( ONE+REXP )*ZLARND( 5, ISEED ) END IF END IF 110 CONTINUE * * Copy the tridiagonal T to AB. * IF( UPPER ) THEN CALL ZCOPY( N-1, WORK, 1, AB( KD, 2 ), LDAB ) CALL ZCOPY( N-2, WORK( N+1 ), 1, AB( KD-1, 3 ), LDAB ) ELSE CALL ZCOPY( N-1, WORK, 1, AB( 2, 1 ), LDAB ) CALL ZCOPY( N-2, WORK( N+1 ), 1, AB( 3, 1 ), LDAB ) END IF END IF * * IMAT > 9: Pathological test cases. These triangular matrices * are badly scaled or badly conditioned, so when used in solving a * triangular system they may cause overflow in the solution vector. * ELSE IF( IMAT.EQ.10 ) THEN * * Type 10: Generate a triangular matrix with elements between * -1 and 1. Give the diagonal norm 2 to make it well-conditioned. * Make the right hand side large so that it requires scaling. * IF( UPPER ) THEN DO 120 J = 1, N LENJ = MIN( J-1, KD ) CALL ZLARNV( 4, ISEED, LENJ, AB( KD+1-LENJ, J ) ) AB( KD+1, J ) = ZLARND( 5, ISEED )*TWO 120 CONTINUE ELSE DO 130 J = 1, N LENJ = MIN( N-J, KD ) IF( LENJ.GT.0 ) $ CALL ZLARNV( 4, ISEED, LENJ, AB( 2, J ) ) AB( 1, J ) = ZLARND( 5, ISEED )*TWO 130 CONTINUE END IF * * Set the right hand side so that the largest value is BIGNUM. * CALL ZLARNV( 2, ISEED, N, B ) IY = IZAMAX( N, B, 1 ) BNORM = ABS( B( IY ) ) BSCAL = BIGNUM / MAX( ONE, BNORM ) CALL ZDSCAL( N, BSCAL, B, 1 ) * ELSE IF( IMAT.EQ.11 ) THEN * * Type 11: Make the first diagonal element in the solve small to * cause immediate overflow when dividing by T(j,j). * In type 11, the offdiagonal elements are small (CNORM(j) < 1). * CALL ZLARNV( 2, ISEED, N, B ) TSCAL = ONE / DBLE( KD+1 ) IF( UPPER ) THEN DO 140 J = 1, N LENJ = MIN( J-1, KD ) IF( LENJ.GT.0 ) THEN CALL ZLARNV( 4, ISEED, LENJ, AB( KD+2-LENJ, J ) ) CALL ZDSCAL( LENJ, TSCAL, AB( KD+2-LENJ, J ), 1 ) END IF AB( KD+1, J ) = ZLARND( 5, ISEED ) 140 CONTINUE AB( KD+1, N ) = SMLNUM*AB( KD+1, N ) ELSE DO 150 J = 1, N LENJ = MIN( N-J, KD ) IF( LENJ.GT.0 ) THEN CALL ZLARNV( 4, ISEED, LENJ, AB( 2, J ) ) CALL ZDSCAL( LENJ, TSCAL, AB( 2, J ), 1 ) END IF AB( 1, J ) = ZLARND( 5, ISEED ) 150 CONTINUE AB( 1, 1 ) = SMLNUM*AB( 1, 1 ) END IF * ELSE IF( IMAT.EQ.12 ) THEN * * Type 12: Make the first diagonal element in the solve small to * cause immediate overflow when dividing by T(j,j). * In type 12, the offdiagonal elements are O(1) (CNORM(j) > 1). * CALL ZLARNV( 2, ISEED, N, B ) IF( UPPER ) THEN DO 160 J = 1, N LENJ = MIN( J-1, KD ) IF( LENJ.GT.0 ) $ CALL ZLARNV( 4, ISEED, LENJ, AB( KD+2-LENJ, J ) ) AB( KD+1, J ) = ZLARND( 5, ISEED ) 160 CONTINUE AB( KD+1, N ) = SMLNUM*AB( KD+1, N ) ELSE DO 170 J = 1, N LENJ = MIN( N-J, KD ) IF( LENJ.GT.0 ) $ CALL ZLARNV( 4, ISEED, LENJ, AB( 2, J ) ) AB( 1, J ) = ZLARND( 5, ISEED ) 170 CONTINUE AB( 1, 1 ) = SMLNUM*AB( 1, 1 ) END IF * ELSE IF( IMAT.EQ.13 ) THEN * * Type 13: T is diagonal with small numbers on the diagonal to * make the growth factor underflow, but a small right hand side * chosen so that the solution does not overflow. * IF( UPPER ) THEN JCOUNT = 1 DO 190 J = N, 1, -1 DO 180 I = MAX( 1, KD+1-( J-1 ) ), KD AB( I, J ) = ZERO 180 CONTINUE IF( JCOUNT.LE.2 ) THEN AB( KD+1, J ) = SMLNUM*ZLARND( 5, ISEED ) ELSE AB( KD+1, J ) = ZLARND( 5, ISEED ) END IF JCOUNT = JCOUNT + 1 IF( JCOUNT.GT.4 ) $ JCOUNT = 1 190 CONTINUE ELSE JCOUNT = 1 DO 210 J = 1, N DO 200 I = 2, MIN( N-J+1, KD+1 ) AB( I, J ) = ZERO 200 CONTINUE IF( JCOUNT.LE.2 ) THEN AB( 1, J ) = SMLNUM*ZLARND( 5, ISEED ) ELSE AB( 1, J ) = ZLARND( 5, ISEED ) END IF JCOUNT = JCOUNT + 1 IF( JCOUNT.GT.4 ) $ JCOUNT = 1 210 CONTINUE END IF * * Set the right hand side alternately zero and small. * IF( UPPER ) THEN B( 1 ) = ZERO DO 220 I = N, 2, -2 B( I ) = ZERO B( I-1 ) = SMLNUM*ZLARND( 5, ISEED ) 220 CONTINUE ELSE B( N ) = ZERO DO 230 I = 1, N - 1, 2 B( I ) = ZERO B( I+1 ) = SMLNUM*ZLARND( 5, ISEED ) 230 CONTINUE END IF * ELSE IF( IMAT.EQ.14 ) THEN * * Type 14: Make the diagonal elements small to cause gradual * overflow when dividing by T(j,j). To control the amount of * scaling needed, the matrix is bidiagonal. * TEXP = ONE / DBLE( KD+1 ) TSCAL = SMLNUM**TEXP CALL ZLARNV( 4, ISEED, N, B ) IF( UPPER ) THEN DO 250 J = 1, N DO 240 I = MAX( 1, KD+2-J ), KD AB( I, J ) = ZERO 240 CONTINUE IF( J.GT.1 .AND. KD.GT.0 ) $ AB( KD, J ) = DCMPLX( -ONE, -ONE ) AB( KD+1, J ) = TSCAL*ZLARND( 5, ISEED ) 250 CONTINUE B( N ) = DCMPLX( ONE, ONE ) ELSE DO 270 J = 1, N DO 260 I = 3, MIN( N-J+1, KD+1 ) AB( I, J ) = ZERO 260 CONTINUE IF( J.LT.N .AND. KD.GT.0 ) $ AB( 2, J ) = DCMPLX( -ONE, -ONE ) AB( 1, J ) = TSCAL*ZLARND( 5, ISEED ) 270 CONTINUE B( 1 ) = DCMPLX( ONE, ONE ) END IF * ELSE IF( IMAT.EQ.15 ) THEN * * Type 15: One zero diagonal element. * IY = N / 2 + 1 IF( UPPER ) THEN DO 280 J = 1, N LENJ = MIN( J, KD+1 ) CALL ZLARNV( 4, ISEED, LENJ, AB( KD+2-LENJ, J ) ) IF( J.NE.IY ) THEN AB( KD+1, J ) = ZLARND( 5, ISEED )*TWO ELSE AB( KD+1, J ) = ZERO END IF 280 CONTINUE ELSE DO 290 J = 1, N LENJ = MIN( N-J+1, KD+1 ) CALL ZLARNV( 4, ISEED, LENJ, AB( 1, J ) ) IF( J.NE.IY ) THEN AB( 1, J ) = ZLARND( 5, ISEED )*TWO ELSE AB( 1, J ) = ZERO END IF 290 CONTINUE END IF CALL ZLARNV( 2, ISEED, N, B ) CALL ZDSCAL( N, TWO, B, 1 ) * ELSE IF( IMAT.EQ.16 ) THEN * * Type 16: Make the offdiagonal elements large to cause overflow * when adding a column of T. In the non-transposed case, the * matrix is constructed to cause overflow when adding a column in * every other step. * TSCAL = UNFL / ULP TSCAL = ( ONE-ULP ) / TSCAL DO 310 J = 1, N DO 300 I = 1, KD + 1 AB( I, J ) = ZERO 300 CONTINUE 310 CONTINUE TEXP = ONE IF( KD.GT.0 ) THEN IF( UPPER ) THEN DO 330 J = N, 1, -KD DO 320 I = J, MAX( 1, J-KD+1 ), -2 AB( 1+( J-I ), I ) = -TSCAL / DBLE( KD+2 ) AB( KD+1, I ) = ONE B( I ) = TEXP*( ONE-ULP ) IF( I.GT.MAX( 1, J-KD+1 ) ) THEN AB( 2+( J-I ), I-1 ) = -( TSCAL / DBLE( KD+2 ) ) $ / DBLE( KD+3 ) AB( KD+1, I-1 ) = ONE B( I-1 ) = TEXP*DBLE( ( KD+1 )*( KD+1 )+KD ) END IF TEXP = TEXP*TWO 320 CONTINUE B( MAX( 1, J-KD+1 ) ) = ( DBLE( KD+2 ) / $ DBLE( KD+3 ) )*TSCAL 330 CONTINUE ELSE DO 350 J = 1, N, KD TEXP = ONE LENJ = MIN( KD+1, N-J+1 ) DO 340 I = J, MIN( N, J+KD-1 ), 2 AB( LENJ-( I-J ), J ) = -TSCAL / DBLE( KD+2 ) AB( 1, J ) = ONE B( J ) = TEXP*( ONE-ULP ) IF( I.LT.MIN( N, J+KD-1 ) ) THEN AB( LENJ-( I-J+1 ), I+1 ) = -( TSCAL / $ DBLE( KD+2 ) ) / DBLE( KD+3 ) AB( 1, I+1 ) = ONE B( I+1 ) = TEXP*DBLE( ( KD+1 )*( KD+1 )+KD ) END IF TEXP = TEXP*TWO 340 CONTINUE B( MIN( N, J+KD-1 ) ) = ( DBLE( KD+2 ) / $ DBLE( KD+3 ) )*TSCAL 350 CONTINUE END IF END IF * ELSE IF( IMAT.EQ.17 ) THEN * * Type 17: Generate a unit triangular matrix with elements * between -1 and 1, and make the right hand side large so that it * requires scaling. * IF( UPPER ) THEN DO 360 J = 1, N LENJ = MIN( J-1, KD ) CALL ZLARNV( 4, ISEED, LENJ, AB( KD+1-LENJ, J ) ) AB( KD+1, J ) = DBLE( J ) 360 CONTINUE ELSE DO 370 J = 1, N LENJ = MIN( N-J, KD ) IF( LENJ.GT.0 ) $ CALL ZLARNV( 4, ISEED, LENJ, AB( 2, J ) ) AB( 1, J ) = DBLE( J ) 370 CONTINUE END IF * * Set the right hand side so that the largest value is BIGNUM. * CALL ZLARNV( 2, ISEED, N, B ) IY = IZAMAX( N, B, 1 ) BNORM = ABS( B( IY ) ) BSCAL = BIGNUM / MAX( ONE, BNORM ) CALL ZDSCAL( N, BSCAL, B, 1 ) * ELSE IF( IMAT.EQ.18 ) THEN * * Type 18: Generate a triangular matrix with elements between * BIGNUM/(KD+1) and BIGNUM so that at least one of the column * norms will exceed BIGNUM. * 1/3/91: ZLATBS no longer can handle this case * TLEFT = BIGNUM / DBLE( KD+1 ) TSCAL = BIGNUM*( DBLE( KD+1 ) / DBLE( KD+2 ) ) IF( UPPER ) THEN DO 390 J = 1, N LENJ = MIN( J, KD+1 ) CALL ZLARNV( 5, ISEED, LENJ, AB( KD+2-LENJ, J ) ) CALL DLARNV( 1, ISEED, LENJ, RWORK( KD+2-LENJ ) ) DO 380 I = KD + 2 - LENJ, KD + 1 AB( I, J ) = AB( I, J )*( TLEFT+RWORK( I )*TSCAL ) 380 CONTINUE 390 CONTINUE ELSE DO 410 J = 1, N LENJ = MIN( N-J+1, KD+1 ) CALL ZLARNV( 5, ISEED, LENJ, AB( 1, J ) ) CALL DLARNV( 1, ISEED, LENJ, RWORK ) DO 400 I = 1, LENJ AB( I, J ) = AB( I, J )*( TLEFT+RWORK( I )*TSCAL ) 400 CONTINUE 410 CONTINUE END IF CALL ZLARNV( 2, ISEED, N, B ) CALL ZDSCAL( N, TWO, B, 1 ) END IF * * Flip the matrix if the transpose will be used. * IF( .NOT.LSAME( TRANS, 'N' ) ) THEN IF( UPPER ) THEN DO 420 J = 1, N / 2 LENJ = MIN( N-2*J+1, KD+1 ) CALL ZSWAP( LENJ, AB( KD+1, J ), LDAB-1, $ AB( KD+2-LENJ, N-J+1 ), -1 ) 420 CONTINUE ELSE DO 430 J = 1, N / 2 LENJ = MIN( N-2*J+1, KD+1 ) CALL ZSWAP( LENJ, AB( 1, J ), 1, AB( LENJ, N-J+2-LENJ ), $ -LDAB+1 ) 430 CONTINUE END IF END IF * RETURN * * End of ZLATTB * END