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dgecxx.f: added 'On exit' parameter descriptions to DESEL_ROWS and SEL_DESEL_COLS, since they are modified on output.

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1) added 'On exit' parameter descriptions to DESEL_ROWS and SEL_DESEL_COLS, since they are modified on output.

2) For row deselection, changed:

                   IPIV( I ) = IPIV( MSUB )
                  IPIV( MSUB ) = I
                  ITEMP = DESEL_ROWS( I )
                  DESEL_ROWS( I ) = DESEL_ROWS( MSUB )
                  DESEL_ROWS( MSUB ) = ITEMP    into:

into
                  IPIV( I ) = IPIV( MSUB )
                  IPIV( MSUB ) = I
                  DESEL_ROWS( MSUB ) = DESEL_ROWS( I )
                  DESEL_ROWS( I ) = -1

2) cleaned up comments in the code dgecxx.f

modified:   SRC/dgecxx.f
This commit is contained in:
scr2016
2026-04-28 19:20:54 -07:00
parent 7940afb9f9
commit ed5b8231df
1 changed files with 36 additions and 20 deletions
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SRC/dgecxx.f
+36 -20
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@@ -169,8 +169,8 @@
*> of selected columns would be K = N_sel. Otherwise, the factorization
*> routine finds a new column to select with the maximum column 2-norm
*> in the residual A(N_sel+1:M_sub,N_sel+1:N_sub), and swaps that
*> column with the first column of A(1:M,N_sel+1:N_sub). Then the routine
*> checks if the stopping criteria are met in the next residual
*> column with the first column of A(1:M,N_sel+1:N_sub). Then the
*> routine checks if the stopping criteria are met in the next residual
*> A(N_sel+2:M_sub,N_sel+2:N_sub), and so on.
*>
*> Computation of the matrix factors.
@@ -268,13 +268,14 @@
*> The number of columns of the matrix A. N >= 0.
*> \endverbatim
*>
*> \param[in] DESEL_ROWS
*> \param[in,out] DESEL_ROWS
*> \verbatim
*> DESEL_ROWS is INTEGER array, dimension (M)
*> DESEL_ROWS is only accessed if USESD = 'R' or 'A'.
*> This is a row deselection mask array that separates
*> the rows of matrix A into 2 sets.
*>
*> On entry:
*> a) If DESEL_ROWS(i) = -1, the i-th row of the matrix A is
*> deselected by the user, i.e. chosen to be excluded from
*> the column selection algorithm (in both preselection and
@@ -289,15 +290,22 @@
*> the algorithm will use to select columns.
*> After the permutation, this set will be at the top
*> of the matrix A.
*>
*> On exit:
*> DESEL_ROWS will be permutted according to IPIV(i),
*> so that, if IPIV(i) = k, then the entry i of DESEL_ROWS
*> on exit was the entry k of DESEL_ROWS on entry.
*>
*> \endverbatim
*>
*> \param[in] SEL_DESEL_COLS
*> \param[in,out] SEL_DESEL_COLS
*> \verbatim
*> SEL_DESEL_COLS is INTEGER array, dimension (N)
*> SEL_DESEL_COLS is only accessed if USESD = 'C' or 'A'.
*> This is a column preselection-deselection mask array that
*> separates the columns of matrix A into 3 sets.
*>
*> On entry:
*> a) If SEL_DESEL_COLS(j) = +1, the j-th column of the matrix
*> A is preselected by the user to be included
*> in the factor C and will be permuted to the left side
@@ -312,10 +320,16 @@
*>
*> c) If SEL_DESEL_COLS(j) is not equal to 1 and not equal
*> to -1, the j-th column of A is a free column and will be
*> used by the column selection algorithm to determine if this
*> column will be selected. This defines a set of
*> used by the column selection algorithm to determine if
*> this column will be selected. This defines a set of
*> columns of size N_free = N - N_sel - N_desel.
*>
*> On exit:
*> SEL_DESEL_COLS will be permutted according to JPIV(j),
*> so that, if JPIV(j) = k, then the entry j
*> of SEL_DESEL_COLS on exit was the entry k
*> of SEL_DESEL_COLS on entry.
*>
*> NOTE: An error returned as INFO = -6 means that the number
*> of preselected N_sel columns is larger than M_sub.
*> Therefore, the QR factorization of all N_sel preselected
@@ -612,7 +626,7 @@
*> IPIV is INTEGER array, dimension (M)
*> Row permutation indices due to row deselection,
*> for 1 <= i <= M.
*> If IPIV(i)= k, then the row i of A_sub was
*> If IPIV(i) = k, then the row i of A was
*> the row k of A.
*> \endverbatim
*>
@@ -620,7 +634,7 @@
*> \verbatim
*> JPIV is INTEGER array, dimension (N)
*> Column permutation indices, for 1 <= j <= N.
*> If JPIV(j)= k, then the column j of A*P (and of A_sub) was
*> If JPIV(j)= k, then the column j of A*P was
*> the column k of A.
*>
*> The first K elements of the array JPIV contain
@@ -1020,8 +1034,8 @@
*
* a) Test the input workspace size LWORK and LIWORK for the
* minimum size requirement LWKMIN and LIWKMIN respectively.
* b) Determine the optimal workspace sizes LWKOPT and LIWKOPT to be
* returned in WORK( 1 ) and IWORK( 1 ) respectively,
* b) Determine the optimal workspace sizes LWKOPT and LIWKOPT to
* be returned in WORK( 1 ) and IWORK( 1 ) respectively,
* if INFO >= 0 in cases:
* (1) LQUERY = .TRUE.,
* (2) when the routine exits.
@@ -1122,7 +1136,8 @@
IF( RETURNC ) THEN
*
* Integer minimum workspace computation.
* (Int_wk_part_3) LIWKMIN = 2*N for applying the interchanges
* (Int_wk_part_3) LIWKMIN = 2*N for applying the
* interchanges
* for the columns in the matrix C.
*
LIWKMIN = MAX( LIWKMIN, 2*N )
@@ -1259,9 +1274,8 @@
*
IPIV( I ) = IPIV( MSUB )
IPIV( MSUB ) = I
ITEMP = DESEL_ROWS( I )
DESEL_ROWS( I ) = DESEL_ROWS( MSUB )
DESEL_ROWS( MSUB ) = ITEMP
DESEL_ROWS( MSUB ) = DESEL_ROWS( I )
DESEL_ROWS( I ) = -1
END IF
END IF
*
@@ -1272,7 +1286,8 @@
* We do not use the row deselection DESEL_ROWS array.
* Initialize the row pivot array IPIV.
* NOTE: MSUB=M has default value,
* which is set at the beginning of the routine, before argument checks.
* which is set at the beginning of the routine, before argument
* checks.
*
DO I = 1, M, 1
IPIV( I ) = I
@@ -1293,8 +1308,8 @@
IF( USE_SEL_DESEL_COLS ) THEN
*
* Column selection.
* NSEL is the number of selected columns, also the pointer to the last
* selected column.
* NSEL is the number of selected columns, also the pointer to
* the last selected column.
*
NSEL = 0
DO J = 1, N, 1
@@ -1302,7 +1317,7 @@
* Initialize column pivot array JPIV.
JPIV( J ) = J
*
IF( SEL_DESEL_COLS(J).EQ.1 ) THEN
IF( SEL_DESEL_COLS( J ).EQ.1 ) THEN
NSEL = NSEL + 1
*
* This is the check whether the selected column is
@@ -1355,7 +1370,8 @@
* SEL_DESEL_COLS array.
* Initialize column pivot array JPIV.
* NOTE: NSUB=N has default value,
* which is set at the beginning of the routine, before argument checks.
* which is set at the beginning of the routine, before argument
* checks.
*
DO J = 1, N, 1
JPIV( J ) = J
@@ -1637,7 +1653,7 @@
*
* We need to use C and A to compute X = pseudoinv(C) * A, as
* the linear least squares solution to the overdetermined system
* C*X = A. We use LLS routin that uses the QR factorization. For
* C*X = A. We use LLS routine that uses the QR factorization. For
* that purpose, we store the matrix C into the array QRC.
* The matrix A was copied into the array X at the beginning
* of the routine.