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    1: *> \brief \b DLAT2S converts a double-precision triangular matrix to a single-precision triangular matrix.
    2: *
    3: *  =========== DOCUMENTATION ===========
    4: *
    5: * Online html documentation available at 
    6: *            http://www.netlib.org/lapack/explore-html/ 
    7: *
    8: *> \htmlonly
    9: *> Download DLAT2S + dependencies 
   10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlat2s.f"> 
   11: *> [TGZ]</a> 
   12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlat2s.f"> 
   13: *> [ZIP]</a> 
   14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlat2s.f"> 
   15: *> [TXT]</a>
   16: *> \endhtmlonly 
   17: *
   18: *  Definition:
   19: *  ===========
   20: *
   21: *       SUBROUTINE DLAT2S( UPLO, N, A, LDA, SA, LDSA, INFO )
   22: * 
   23: *       .. Scalar Arguments ..
   24: *       CHARACTER          UPLO
   25: *       INTEGER            INFO, LDA, LDSA, N
   26: *       ..
   27: *       .. Array Arguments ..
   28: *       REAL               SA( LDSA, * )
   29: *       DOUBLE PRECISION   A( LDA, * )
   30: *       ..
   31: *  
   32: *
   33: *> \par Purpose:
   34: *  =============
   35: *>
   36: *> \verbatim
   37: *>
   38: *> DLAT2S converts a DOUBLE PRECISION triangular matrix, SA, to a SINGLE
   39: *> PRECISION triangular matrix, A.
   40: *>
   41: *> RMAX is the overflow for the SINGLE PRECISION arithmetic
   42: *> DLAS2S checks that all the entries of A are between -RMAX and
   43: *> RMAX. If not the convertion is aborted and a flag is raised.
   44: *>
   45: *> This is an auxiliary routine so there is no argument checking.
   46: *> \endverbatim
   47: *
   48: *  Arguments:
   49: *  ==========
   50: *
   51: *> \param[in] UPLO
   52: *> \verbatim
   53: *>          UPLO is CHARACTER*1
   54: *>          = 'U':  A is upper triangular;
   55: *>          = 'L':  A is lower triangular.
   56: *> \endverbatim
   57: *>
   58: *> \param[in] N
   59: *> \verbatim
   60: *>          N is INTEGER
   61: *>          The number of rows and columns of the matrix A.  N >= 0.
   62: *> \endverbatim
   63: *>
   64: *> \param[in] A
   65: *> \verbatim
   66: *>          A is DOUBLE PRECISION array, dimension (LDA,N)
   67: *>          On entry, the N-by-N triangular coefficient matrix A.
   68: *> \endverbatim
   69: *>
   70: *> \param[in] LDA
   71: *> \verbatim
   72: *>          LDA is INTEGER
   73: *>          The leading dimension of the array A.  LDA >= max(1,N).
   74: *> \endverbatim
   75: *>
   76: *> \param[out] SA
   77: *> \verbatim
   78: *>          SA is REAL array, dimension (LDSA,N)
   79: *>          Only the UPLO part of SA is referenced.  On exit, if INFO=0,
   80: *>          the N-by-N coefficient matrix SA; if INFO>0, the content of
   81: *>          the UPLO part of SA is unspecified.
   82: *> \endverbatim
   83: *>
   84: *> \param[in] LDSA
   85: *> \verbatim
   86: *>          LDSA is INTEGER
   87: *>          The leading dimension of the array SA.  LDSA >= max(1,M).
   88: *> \endverbatim
   89: *>
   90: *> \param[out] INFO
   91: *> \verbatim
   92: *>          INFO is INTEGER
   93: *>          = 0:  successful exit.
   94: *>          = 1:  an entry of the matrix A is greater than the SINGLE
   95: *>                PRECISION overflow threshold, in this case, the content
   96: *>                of the UPLO part of SA in exit is unspecified.
   97: *> \endverbatim
   98: *
   99: *  Authors:
  100: *  ========
  101: *
  102: *> \author Univ. of Tennessee 
  103: *> \author Univ. of California Berkeley 
  104: *> \author Univ. of Colorado Denver 
  105: *> \author NAG Ltd. 
  106: *
  107: *> \date September 2012
  108: *
  109: *> \ingroup doubleOTHERauxiliary
  110: *
  111: *  =====================================================================
  112:       SUBROUTINE DLAT2S( UPLO, N, A, LDA, SA, LDSA, INFO )
  113: *
  114: *  -- LAPACK auxiliary routine (version 3.4.2) --
  115: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
  116: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
  117: *     September 2012
  118: *
  119: *     .. Scalar Arguments ..
  120:       CHARACTER          UPLO
  121:       INTEGER            INFO, LDA, LDSA, N
  122: *     ..
  123: *     .. Array Arguments ..
  124:       REAL               SA( LDSA, * )
  125:       DOUBLE PRECISION   A( LDA, * )
  126: *     ..
  127: *
  128: *  =====================================================================
  129: *
  130: *     .. Local Scalars ..
  131:       INTEGER            I, J
  132:       DOUBLE PRECISION   RMAX
  133:       LOGICAL            UPPER
  134: *     ..
  135: *     .. External Functions ..
  136:       REAL               SLAMCH
  137:       LOGICAL            LSAME
  138:       EXTERNAL           SLAMCH, LSAME
  139: *     ..
  140: *     .. Executable Statements ..
  141: *
  142:       RMAX = SLAMCH( 'O' )
  143:       UPPER = LSAME( UPLO, 'U' )
  144:       IF( UPPER ) THEN
  145:          DO 20 J = 1, N
  146:             DO 10 I = 1, J
  147:                IF( ( A( I, J ).LT.-RMAX ) .OR. ( A( I, J ).GT.RMAX ) )
  148:      $             THEN
  149:                   INFO = 1
  150:                   GO TO 50
  151:                END IF
  152:                SA( I, J ) = A( I, J )
  153:    10       CONTINUE
  154:    20    CONTINUE
  155:       ELSE
  156:          DO 40 J = 1, N
  157:             DO 30 I = J, N
  158:                IF( ( A( I, J ).LT.-RMAX ) .OR. ( A( I, J ).GT.RMAX ) )
  159:      $             THEN
  160:                   INFO = 1
  161:                   GO TO 50
  162:                END IF
  163:                SA( I, J ) = A( I, J )
  164:    30       CONTINUE
  165:    40    CONTINUE
  166:       END IF
  167:    50 CONTINUE
  168: *
  169:       RETURN
  170: *
  171: *     End of DLAT2S
  172: *
  173:       END