forked from lijiext/lammps
122 lines
3.0 KiB
Fortran
122 lines
3.0 KiB
Fortran
*> \brief \b ILADLR scans a matrix for its last non-zero row.
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*
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* =========== DOCUMENTATION ===========
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*
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* Online html documentation available at
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* http://www.netlib.org/lapack/explore-html/
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*
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*> \htmlonly
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*> Download ILADLR + dependencies
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/iladlr.f">
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*> [TGZ]</a>
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/iladlr.f">
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*> [ZIP]</a>
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/iladlr.f">
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*> [TXT]</a>
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*> \endhtmlonly
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*
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* Definition:
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* ===========
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*
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* INTEGER FUNCTION ILADLR( M, N, A, LDA )
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*
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* .. Scalar Arguments ..
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* INTEGER M, N, LDA
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* ..
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* .. Array Arguments ..
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* DOUBLE PRECISION A( LDA, * )
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* ..
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*
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*
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*> \par Purpose:
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* =============
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*>
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*> \verbatim
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*>
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*> ILADLR scans A for its last non-zero row.
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*> \endverbatim
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*
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* Arguments:
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* ==========
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*
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*> \param[in] M
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*> \verbatim
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*> M is INTEGER
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*> The number of rows of the matrix A.
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*> \endverbatim
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*>
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*> \param[in] N
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*> \verbatim
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*> N is INTEGER
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*> The number of columns of the matrix A.
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*> \endverbatim
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*>
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*> \param[in] A
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*> \verbatim
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*> A is DOUBLE PRECISION array, dimension (LDA,N)
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*> The m by n matrix A.
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*> \endverbatim
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*>
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*> \param[in] LDA
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*> \verbatim
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*> LDA is INTEGER
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*> The leading dimension of the array A. LDA >= max(1,M).
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*> \endverbatim
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*
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* Authors:
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* ========
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*
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*> \author Univ. of Tennessee
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*> \author Univ. of California Berkeley
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*> \author Univ. of Colorado Denver
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*> \author NAG Ltd.
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*
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*> \date December 2016
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*
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*> \ingroup OTHERauxiliary
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*
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* =====================================================================
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INTEGER FUNCTION ILADLR( M, N, A, LDA )
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*
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* -- LAPACK auxiliary routine (version 3.7.0) --
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* -- LAPACK is a software package provided by Univ. of Tennessee, --
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* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
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* December 2016
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*
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* .. Scalar Arguments ..
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INTEGER M, N, LDA
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* ..
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* .. Array Arguments ..
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DOUBLE PRECISION A( LDA, * )
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* ..
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*
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* =====================================================================
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*
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* .. Parameters ..
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DOUBLE PRECISION ZERO
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PARAMETER ( ZERO = 0.0D+0 )
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* ..
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* .. Local Scalars ..
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INTEGER I, J
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* ..
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* .. Executable Statements ..
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*
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* Quick test for the common case where one corner is non-zero.
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IF( M.EQ.0 ) THEN
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ILADLR = M
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ELSE IF( A(M, 1).NE.ZERO .OR. A(M, N).NE.ZERO ) THEN
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ILADLR = M
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ELSE
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* Scan up each column tracking the last zero row seen.
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ILADLR = 0
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DO J = 1, N
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I=M
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DO WHILE((A(MAX(I,1),J).EQ.ZERO).AND.(I.GE.1))
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I=I-1
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ENDDO
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ILADLR = MAX( ILADLR, I )
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END DO
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END IF
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RETURN
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END
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