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Annotation of rpl/lapack/lapack/dlat2s.f, revision 1.3

1.1       bertrand    1:       SUBROUTINE DLAT2S( UPLO, N, A, LDA, SA, LDSA, INFO )
                      2: *
                      3: *  -- LAPACK PROTOTYPE auxiliary routine (version 3.1.2) --
                      4: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
                      5: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
                      6: *     May 2007
                      7: *
                      8: *     .. Scalar Arguments ..
                      9:       CHARACTER          UPLO
                     10:       INTEGER            INFO, LDA, LDSA, N
                     11: *     ..
                     12: *     .. Array Arguments ..
                     13:       REAL               SA( LDSA, * )
                     14:       DOUBLE PRECISION   A( LDA, * )
                     15: *     ..
                     16: *
                     17: *  Purpose
                     18: *  =======
                     19: *
                     20: *  DLAT2S converts a DOUBLE PRECISION triangular matrix, SA, to a SINGLE
                     21: *  PRECISION triangular matrix, A.
                     22: *
                     23: *  RMAX is the overflow for the SINGLE PRECISION arithmetic
                     24: *  DLAS2S checks that all the entries of A are between -RMAX and
                     25: *  RMAX. If not the convertion is aborted and a flag is raised.
                     26: *
                     27: *  This is an auxiliary routine so there is no argument checking.
                     28: *
                     29: *  Arguments
                     30: *  =========
                     31: *
                     32: *  UPLO    (input) CHARACTER*1
                     33: *          = 'U':  A is upper triangular;
                     34: *          = 'L':  A is lower triangular.
                     35: *
                     36: *  N       (input) INTEGER
                     37: *          The number of rows and columns of the matrix A.  N >= 0.
                     38: *
                     39: *  A       (input) DOUBLE PRECISION array, dimension (LDA,N)
                     40: *          On entry, the N-by-N triangular coefficient matrix A.
                     41: *
                     42: *  LDA     (input) INTEGER
                     43: *          The leading dimension of the array A.  LDA >= max(1,N).
                     44: *
                     45: *  SA      (output) REAL array, dimension (LDSA,N)
                     46: *          Only the UPLO part of SA is referenced.  On exit, if INFO=0,
                     47: *          the N-by-N coefficient matrix SA; if INFO>0, the content of
                     48: *          the UPLO part of SA is unspecified.
                     49: *
                     50: *  LDSA    (input) INTEGER
                     51: *          The leading dimension of the array SA.  LDSA >= max(1,M).
                     52: *
                     53: *  INFO    (output) INTEGER
                     54: *          = 0:  successful exit.
                     55: *          = 1:  an entry of the matrix A is greater than the SINGLE
                     56: *                PRECISION overflow threshold, in this case, the content
                     57: *                of the UPLO part of SA in exit is unspecified.
                     58: *
                     59: *  =========
                     60: *
                     61: *     .. Local Scalars ..
                     62:       INTEGER            I, J
                     63:       DOUBLE PRECISION   RMAX
                     64:       LOGICAL            UPPER
                     65: *     ..
                     66: *     .. External Functions ..
                     67:       REAL               SLAMCH
                     68:       LOGICAL            LSAME
                     69:       EXTERNAL           SLAMCH, LSAME
                     70: *     ..
                     71: *     .. Executable Statements ..
                     72: *
                     73:       RMAX = SLAMCH( 'O' )
                     74:       UPPER = LSAME( UPLO, 'U' )
                     75:       IF( UPPER ) THEN
                     76:          DO 20 J = 1, N
                     77:             DO 10 I = 1, J
                     78:                IF( ( A( I, J ).LT.-RMAX ) .OR. ( A( I, J ).GT.RMAX ) )
                     79:      +             THEN
                     80:                   INFO = 1
                     81:                   GO TO 50
                     82:                END IF
                     83:                SA( I, J ) = A( I, J )
                     84:    10       CONTINUE
                     85:    20    CONTINUE
                     86:       ELSE
                     87:          DO 40 J = 1, N
                     88:             DO 30 I = J, N
                     89:                IF( ( A( I, J ).LT.-RMAX ) .OR. ( A( I, J ).GT.RMAX ) )
                     90:      +             THEN
                     91:                   INFO = 1
                     92:                   GO TO 50
                     93:                END IF
                     94:                SA( I, J ) = A( I, J )
                     95:    30       CONTINUE
                     96:    40    CONTINUE
                     97:       END IF
                     98:    50 CONTINUE
                     99: *
                    100:       RETURN
                    101: *
                    102: *     End of DLAT2S
                    103: *
                    104:       END