This a draft for dgecxx.f.#1161
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mgates3
requested changes
Oct 15, 2025
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by mistake 2 branches (one with dgecx.f and one with DGECX.f ) were joined
in a single pull request, the files are identical. DGECX.f can be removed.
…On Wed, Oct 15, 2025 at 11:15 AM Mark Gates ***@***.***> wrote:
***@***.**** requested changes on this pull request.
Some initial comments.
------------------------------
On SRC/DGECX.f
<#1161 (comment)>
:
There is both DGECX.f (incorrect) and dgecx.f (correct) file? This file
should be removed.
------------------------------
In SRC/dgecx.f
<#1161 (comment)>
:
> +*> array as the first K elements.
+*> b) If the flag COMP_X is set, then the routine also explicitly
+*> computes and returns the factor X = pseudoinv(C) * A.
+*>
+*> \endverbatim
+*
+* Arguments:
+* ==========
+*
+*> \param[in] FACT
+*> \verbatim
+*> FACT is CHARACTER*1
+*> Specifies how the factors of CX factorization
+*> are returned.
+*>
+*> = 'P' or 'p' : return only the column permutaion matrix P
Pedantic: LAPACK doesn't normally specify both Uppercase and lowercase.
Cf.:
lapack/SRC> grep "^\*> += '\w'" lapack/SRC/zpotrf.f
*> = 'U': Upper triangle of A is stored;
*> = 'L': Lower triangle of A is stored.
lapack/SRC> grep "^\*> += '\w'" lapack/SRC/*.f`
------------------------------
In SRC/dgecx.f
<#1161 (comment)>
:
> +*>
+*> If LWORK = -1, then a workspace query is assumed; the routine
+*> only calculates the optimal size of the WORK array, returns
+*> this value as the first entry of the WORK array, and no error
+*> message related to LWORK is issued by XERBLA.
+*> \endverbatim
+*>
+*> \param[out] IWORK
+*> \verbatim
+*> IWORK is INTEGER array, dimension (N).
+*> Is a work array. ( IWORK is used by DGEQP3RK to store indices
+*> of "bad" columns for norm downdating in the residual
+*> matrix in the blocked step auxiliary subroutine DLAQP3RK ).
+*> \endverbatim
+*>
+*> \param[out] LIWORK
Input, right? \param[in]
------------------------------
In SRC/dgecx.f
<#1161 (comment)>
:
> +*>
+*> \param[out] IWORK
+*> \verbatim
+*> IWORK is INTEGER array, dimension (N).
+*> Is a work array. ( IWORK is used by DGEQP3RK to store indices
+*> of "bad" columns for norm downdating in the residual
+*> matrix in the blocked step auxiliary subroutine DLAQP3RK ).
+*> \endverbatim
+*>
+*> \param[out] LIWORK
+*> \verbatim
+*> LIWORK is INTEGER
+*> The dimension of the array LIWORK. LIWORK >= N
+*>
+*> If LIWORK = -1, then a workspace query is assumed; the routine
+*> only calculates the optimal size of the WORK array, returns
Typo: IWORK array.
------------------------------
In SRC/dgecx.f
<#1161 (comment)>
:
> +* Copy matrix C into work array WORK.
+*
+ CALL DLACPY( 'F', M, K, C, LDC, WORK, M )
+*
+ CALL DGELS( 'N', M, K, N, WORK, M, X, LDX,
+ $ WORK( M*K+1 ), LWORK,
+ $ IINFO )
+ INFO = IINFO
+*
+ END IF
+*
+ WORK( 1 ) = DBLE( LWKOPT )
+*
+* DGECX
+*
+ END
Files should end with a newline. Notice ⊖ on Github.
------------------------------
In SRC/dgecx.f
<#1161 (comment)>
:
> +* code.
+*
+ IF( INFO.EQ.0 ) THEN
+ MINMN = MIN( M, N )
+ IF( MINMN.EQ.0 ) THEN
+ LWKMIN = 1
+ LWKOPT = 1
+ ELSE
+ LWKMIN = 3*N + 1
+*
+* Assign to NBOPT optimal block size.
+*
+ NBOPT = ILAENV( INB, 'DGEQRF', ' ', M, N, -1, -1 )
+ LWKOPT = 1000
+ END IF
+ WORK( 1 ) = DBLE( LWKOPT )
Add:
LWORK( 1 ) = N
or whatever the formula is. Also elsewhere.
------------------------------
In SRC/dgecx.f
<#1161 (comment)>
:
> +* that uses QR factorization. For that purpose, we store C into
+* WORK array WORK(1:M*K), and the matrix A was copied into
+* the array X at the begining of the routine.
+*
+* Copy matrix C into work array WORK.
+*
+ CALL DLACPY( 'F', M, K, C, LDC, WORK, M )
+*
+ CALL DGELS( 'N', M, K, N, WORK, M, X, LDX,
+ $ WORK( M*K+1 ), LWORK,
+ $ IINFO )
+ INFO = IINFO
+*
+ END IF
+*
+ WORK( 1 ) = DBLE( LWKOPT )
Add:
LWORK( 1 ) = N
as above.
------------------------------
In SRC/dgecx.f
<#1161 (comment)>
:
> +*
+ MNSUB = MIN(MSUB, NSUB)
+ MRESID = MSUB-NSEL
+ NRESID = NSUB-NSEL
+ IF( NSEL.GT.0 ) THEN
+ IF( MSUB.LT.NSEL ) THEN
+* TODO: Move this part to the top of the routine.
+* a) Case MSUB < NSEL.
+* When the number of preselected columns
+* is larger than MSUB, hence the factorization of all NSEL
+* columns cannot be completed. Return from the routine with the
+* error of COL_SEL_DESEL parameter. NSEL cannot be larger than
+* MSUB.
+*
+ INFO = -6
+ WORK( 1 ) = DBLE( LWKOPT )
Add:
LWORK( 1 ) = N
or whatever the formula is. Also elsewhere.
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changed the description of DGECX
ilayn
reviewed
Oct 16, 2025
Collaborator
|
We've discussed that this is the expert interface, and we would have a simplified interface (e.g., without all the column selection). Elsewhere in LAPACK, expert interfaces have an extra |
mgates3
reviewed
Nov 12, 2025
mgates3
reviewed
Nov 12, 2025
mgates3
requested changes
Nov 12, 2025
…efined calculation for workspace LWORK and LIWORK
…to include NX crosspver point
…CT = 'X', LDX >= max(1,M) to LDX >= max(1,min(M,N))
… of LDX to now say again If FACT = 'X', LDX >= max(1,M), plus expanded the description of the parameter X.
…em as min|| A - C*X||_F for the unknown X
Quick rfturn if possible for
a) M = 0 or N = 0. There is no matrix A(1:M,1:N).
b) MSUB = 0 or NSUB = 0. There is no matrix A_sub(1:MSUB,1:NSUB).
modified: SRC/dgecxx.f
modified: SRC/dgecxx.f
mgates3
reviewed
Apr 29, 2026
Comment on lines
44
to
47
| *> \par Purpose: | ||
| * ============= | ||
| *> | ||
| *> \verbatim |
Collaborator
There was a problem hiding this comment.
Doing doxygen DOCS/Doxyfile or make html both worked for me. The dgecxx page looks normal. If you don't have dot installed, it won't create a call graph.
…L_DESEL_COLS, since they are modified on output.
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
In case, when we return the matrrix X as well, we use the copy of the origonal matrix A that is stored in X. So that we do not need to save the matrix A into the array C, and do not need to select the columns of A in the array C in place. Instead, we just copy the selected columns of the matrix A into the matrix C. modified: SRC/dgecxx.f
Line 29 was emtied in error while adding at commit ce5b69c index 9980399..7a7c50f 100644 --- a/SRC/lapack_64.h +++ b/SRC/lapack_64.h @@ -26,7 +26,7 @@ #define CGBCON CGBCON_64 #define CGBEQU CGBEQU_64 #define CGBEQUB CGBEQUB_64 - +#define CGBMV CGBMV_64 #define CGBRFS CGBRFS_64 #define CGBRFSX CGBRFSX_64 modified: SRC/lapack_64.h
modified: SRC/dgecxx.f
after NSEL columns and NFREE columns factorization: from update style K = NSEL, and K = NSEL + KFREE to increment style K = K + NSEL, K = K + KFEE modified: SRC/dgecxx.f
since min( M, N) = 0 implies min( MSUB, NSUB) = 0,
changed
From:
IF( MIN( MINMN, MIN( MSUB, NSUB )).EQ.0 ) THEN
K = 0
MAXC2NRMK = ZERO
RELMAXC2NRMK = ZERO
FNRMK = ZERO
RETURN
END IF
To:
IF( MIN( MSUB, NSUB ).EQ.0 ) THEN
K = 0
MAXC2NRMK = ZERO
RELMAXC2NRMK = ZERO
FNRMK = ZERO
RETURN
END IF
modified: SRC/dgecxx.f
modified: SRC/dgecxx.f
modified: SRC/dgecxx.f
cosmetic change modified: SRC/dgecxx.f
Also included sgecxx.f in to SRC/CMakeLists.txt SRC/Makefile and modified SRC/lapack_64.h to reflect the addition SRC/sgecxx.f modified: SRC/CMakeLists.txt modified: SRC/Makefile modified: SRC/lapack_64.h new file: SRC/sgecxx.f
modified: TESTING/LIN/dchkaa.F
also changed Definition sections in the top comments modified: TESTING/LIN/dchkcxx.f
modified: TESTING/LIN/dchkcxx.f
modified: TESTING/LIN/dchkcxx.f
from RESULT( 5 ) = 0D+0 to RESULT( 5 ) = ZERO modified: TESTING/LIN/dchkcxx.f
modified: TESTING/LIN/dchkaa.F
modified: LIN/dchkcxx.f
modified: TESTING/LIN/CMakeLists.txt modified: TESTING/LIN/Makefile modified: TESTING/LIN/schkaa.F new file: TESTING/LIN/schkcxx.f new file: TESTING/LIN/serrcxx.f modified: TESTING/LIN/slatb4.f modified: TESTING/stest.in
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… and LIWORK modified: SRC/dgecxx.f modified: SRC/sgecxx.f
modified: SRC/dgecxx.f modified: SRC/sgecxx.f
modified: SRC/dgecxx.f modified: SRC/sgecxx.f
modified: SRC/CMakeLists.txt modified: SRC/Makefile modified: SRC/lapack_64.h new file: SRC/zgecxx.f
modified: TESTING/LIN/dchkcxx.f modified: TESTING/LIN/schkcxx.f
modified: TESTING/LIN/dchkcxx.f
modified: TESTING/LIN/schkcxx.f
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