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SUBROUTINE DTZPADCPY( UPLO, DIAG, M, N, IOFFD, A, LDA, B, LDB )
*
* -- PBLAS auxiliary routine (version 2.0) --
* University of Tennessee, Knoxville, Oak Ridge National Laboratory,
* and University of California, Berkeley.
* April 1, 1998
*
* .. Scalar Arguments ..
CHARACTER*1 DIAG, UPLO
INTEGER IOFFD, LDA, LDB, M, N
* ..
* .. Array Arguments ..
DOUBLE PRECISION A( LDA, * ), B( LDB, * )
* ..
*
* Purpose
* =======
*
* DTZPADCPY copies an array A into an array B. The unchanged part of B
* is padded with zeros. The diagonal of B specified by IOFFD may be set
* to ones.
*
* Arguments
* =========
*
* UPLO (input) CHARACTER*1
* On entry, UPLO specifies which trapezoidal part of the ar-
* ray A is to be copied as follows:
* = 'L' or 'l': Lower triangular part is copied; the
* strictly upper triangular part of B is
* padded with zeros,
* = 'U' or 'u': Upper triangular part is copied; the
* strictly lower triangular part of B is
* padded with zeros.
*
* DIAG (input) CHARACTER*1
* On entry, DIAG specifies whether or not the diagonal of B is
* to be set to ones or not as follows:
*
* DIAG = 'N' or 'n': the diagonals of A are copied into the
* diagonals of B, otherwise the diagonals of B are set to ones.
*
* M (input) INTEGER
* On entry, M specifies the number of rows of the array A. M
* must be at least zero.
*
* N (input) INTEGER
* On entry, N specifies the number of columns of the array A.
* N must be at least zero.
*
* IOFFD (input) INTEGER
* On entry, IOFFD specifies the position of the offdiagonal de-
* limiting the upper and lower trapezoidal part of A as follows
* (see the notes below):
*
* IOFFD = 0 specifies the main diagonal A( i, i ),
* with i = 1 ... MIN( M, N ),
* IOFFD > 0 specifies the subdiagonal A( i+IOFFD, i ),
* with i = 1 ... MIN( M-IOFFD, N ),
* IOFFD < 0 specifies the superdiagonal A( i, i-IOFFD ),
* with i = 1 ... MIN( M, N+IOFFD ).
*
* A (input) DOUBLE PRECISION array
* On entry, A is an array of dimension (LDA,N). Before entry
* with UPLO = 'U', the leading m by n part of the array A must
* contain the upper trapezoidal part of the matrix to be copied
* as specified by IOFFD, UPLO and DIAG, and the strictly lower
* trapezoidal part of A is not referenced; When UPLO = 'L',the
* leading m by n part of the array A must contain the lower
* trapezoidal part of the matrix to be copied as specified by
* IOFFD, UPLO and DIAG and the strictly upper trapezoidal part
* of A is not referenced.
*
* LDA (input) INTEGER
* On entry, LDA specifies the leading dimension of the array A.
* LDA must be at least max( 1, M ).
*
* B (output) DOUBLE PRECISION array
* On entry, B is an array of dimension (LDB,N). On exit, this
* array contains the padded copy of A as specified by IOFFD,
* UPLO and DIAG.
*
* LDB (input) INTEGER
* On entry, LDB specifies the leading dimension of the array B.
* LDB must be at least max( 1, M ).
*
* Notes
* =====
* N N
* ---------------------------- -----------
* | d | | |
* M | d 'U' | | 'U' |
* | 'L' 'D' | |d |
* | d | M | d |
* ---------------------------- | 'D' |
* | d |
* IOFFD < 0 | 'L' d |
* | d|
* N | |
* ----------- -----------
* | d 'U'|
* | d | IOFFD > 0
* M | 'D' |
* | d| N
* | 'L' | ----------------------------
* | | | 'U' |
* | | |d |
* | | | 'D' |
* | | | d |
* | | |'L' d |
* ----------- ----------------------------
*
* -- Written on April 1, 1998 by
* Antoine Petitet, University of Tennessee, Knoxville 37996, USA.
*
* =====================================================================
*
* .. Parameters ..
DOUBLE PRECISION ONE, ZERO
PARAMETER ( ONE = 1.0D+0, ZERO = 0.0D+0 )
* ..
* .. Local Scalars ..
INTEGER I, ITMP, J, JTMP, MN
* ..
* .. External Functions ..
LOGICAL LSAME
EXTERNAL LSAME
* ..
* .. Intrinsic Functions ..
INTRINSIC MAX, MIN
* .. Executable Statements ..
*
* Quick return if possible
*
IF( M.LE.0 .OR. N.LE.0 )
$ RETURN
*
* Start the operations
*
IF( LSAME( UPLO, 'L' ) ) THEN
*
MN = MAX( 0, -IOFFD )
DO 20 J = 1, MIN( MN, N )
DO 10 I = 1, M
B( I, J ) = A( I, J )
10 CONTINUE
20 CONTINUE
*
JTMP = MIN( M - IOFFD, N )
*
IF( LSAME( DIAG, 'N' ) ) THEN
DO 50 J = MN + 1, JTMP
ITMP = J + IOFFD
DO 30 I = 1, ITMP - 1
B( I, J ) = ZERO
30 CONTINUE
DO 40 I = ITMP, M
B( I, J ) = A( I, J )
40 CONTINUE
50 CONTINUE
ELSE
DO 80 J = MN + 1, JTMP
ITMP = J + IOFFD
DO 60 I = 1, ITMP - 1
B( I, J ) = ZERO
60 CONTINUE
B( ITMP, J ) = ONE
DO 70 I = ITMP + 1, M
B( I, J ) = A( I, J )
70 CONTINUE
80 CONTINUE
END IF
*
DO 100 J = JTMP + 1, N
DO 90 I = 1, M
B( I, J ) = ZERO
90 CONTINUE
100 CONTINUE
*
ELSE IF( LSAME( UPLO, 'U' ) ) THEN
*
JTMP = MAX( 0, -IOFFD )
*
DO 120 J = 1, JTMP
DO 110 I = 1, M
B( I, J ) = ZERO
110 CONTINUE
120 CONTINUE
*
MN = MIN( M - IOFFD, N )
*
IF( LSAME( DIAG, 'N' ) ) THEN
DO 150 J = JTMP + 1, MN
ITMP = J + IOFFD
DO 130 I = 1, ITMP
B( I, J ) = A( I, J )
130 CONTINUE
DO 140 I = ITMP + 1, M
B( I, J ) = ZERO
140 CONTINUE
150 CONTINUE
ELSE
DO 180 J = JTMP + 1, MN
ITMP = J + IOFFD
DO 160 I = 1, ITMP - 1
B( I, J ) = A( I, J )
160 CONTINUE
B( ITMP, J ) = ONE
DO 170 I = ITMP + 1, M
B( I, J ) = ZERO
170 CONTINUE
180 CONTINUE
END IF
*
DO 200 J = MAX( 0, MN ) + 1, N
DO 190 I = 1, M
B( I, J ) = A( I, J )
190 CONTINUE
200 CONTINUE
*
ELSE
*
DO 220 J = 1, N
DO 210 I = 1, M
B( I, J ) = A( I, J )
210 CONTINUE
220 CONTINUE
*
END IF
*
RETURN
*
* End of DTZPADCPY
*
END
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