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Annotation of rpl/lapack/lapack/iladlr.f, revision 1.15

1.14      bertrand    1: *> \brief \b ILADLR scans a matrix for its last non-zero row.
1.10      bertrand    2: *
                      3: *  =========== DOCUMENTATION ===========
                      4: *
                      5: * Online html documentation available at 
                      6: *            http://www.netlib.org/lapack/explore-html/ 
                      7: *
                      8: *> \htmlonly
                      9: *> Download ILADLR + dependencies 
                     10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/iladlr.f"> 
                     11: *> [TGZ]</a> 
                     12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/iladlr.f"> 
                     13: *> [ZIP]</a> 
                     14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/iladlr.f"> 
                     15: *> [TXT]</a>
                     16: *> \endhtmlonly 
                     17: *
                     18: *  Definition:
                     19: *  ===========
                     20: *
                     21: *       INTEGER FUNCTION ILADLR( M, N, A, LDA )
                     22: * 
                     23: *       .. Scalar Arguments ..
                     24: *       INTEGER            M, N, LDA
                     25: *       ..
                     26: *       .. Array Arguments ..
                     27: *       DOUBLE PRECISION   A( LDA, * )
                     28: *       ..
                     29: *  
                     30: *
                     31: *> \par Purpose:
                     32: *  =============
                     33: *>
                     34: *> \verbatim
                     35: *>
                     36: *> ILADLR scans A for its last non-zero row.
                     37: *> \endverbatim
                     38: *
                     39: *  Arguments:
                     40: *  ==========
                     41: *
                     42: *> \param[in] M
                     43: *> \verbatim
                     44: *>          M is INTEGER
                     45: *>          The number of rows of the matrix A.
                     46: *> \endverbatim
                     47: *>
                     48: *> \param[in] N
                     49: *> \verbatim
                     50: *>          N is INTEGER
                     51: *>          The number of columns of the matrix A.
                     52: *> \endverbatim
                     53: *>
                     54: *> \param[in] A
                     55: *> \verbatim
                     56: *>          A is DOUBLE PRECISION array, dimension (LDA,N)
                     57: *>          The m by n matrix A.
                     58: *> \endverbatim
                     59: *>
                     60: *> \param[in] LDA
                     61: *> \verbatim
                     62: *>          LDA is INTEGER
                     63: *>          The leading dimension of the array A. LDA >= max(1,M).
                     64: *> \endverbatim
                     65: *
                     66: *  Authors:
                     67: *  ========
                     68: *
                     69: *> \author Univ. of Tennessee 
                     70: *> \author Univ. of California Berkeley 
                     71: *> \author Univ. of Colorado Denver 
                     72: *> \author NAG Ltd. 
                     73: *
1.14      bertrand   74: *> \date September 2012
1.10      bertrand   75: *
                     76: *> \ingroup auxOTHERauxiliary
                     77: *
                     78: *  =====================================================================
1.5       bertrand   79:       INTEGER FUNCTION ILADLR( M, N, A, LDA )
1.1       bertrand   80: *
1.14      bertrand   81: *  -- LAPACK auxiliary routine (version 3.4.2) --
1.1       bertrand   82: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
                     83: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.14      bertrand   84: *     September 2012
1.1       bertrand   85: *
                     86: *     .. Scalar Arguments ..
                     87:       INTEGER            M, N, LDA
                     88: *     ..
                     89: *     .. Array Arguments ..
                     90:       DOUBLE PRECISION   A( LDA, * )
                     91: *     ..
                     92: *
                     93: *  =====================================================================
                     94: *
                     95: *     .. Parameters ..
                     96:       DOUBLE PRECISION ZERO
                     97:       PARAMETER ( ZERO = 0.0D+0 )
                     98: *     ..
                     99: *     .. Local Scalars ..
                    100:       INTEGER I, J
                    101: *     ..
                    102: *     .. Executable Statements ..
                    103: *
                    104: *     Quick test for the common case where one corner is non-zero.
                    105:       IF( M.EQ.0 ) THEN
                    106:          ILADLR = M
                    107:       ELSE IF( A(M, 1).NE.ZERO .OR. A(M, N).NE.ZERO ) THEN
                    108:          ILADLR = M
                    109:       ELSE
                    110: *     Scan up each column tracking the last zero row seen.
                    111:          ILADLR = 0
                    112:          DO J = 1, N
1.9       bertrand  113:             I=M
1.12      bertrand  114:             DO WHILE((A(MAX(I,1),J).EQ.ZERO).AND.(I.GE.1))
                    115:                I=I-1
1.9       bertrand  116:             ENDDO
1.1       bertrand  117:             ILADLR = MAX( ILADLR, I )
                    118:          END DO
                    119:       END IF
                    120:       RETURN
1.5       bertrand  121:       END