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SUBROUTINE DLASET( UPLO, M, N, ALPHA, BETA, A, LDA )
*
* -- LAPACK auxiliary routine (version 3.1) --
* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
* November 2006
*
* .. Scalar Arguments ..
CHARACTER UPLO
INTEGER LDA, M, N
DOUBLE PRECISION ALPHA, BETA
* ..
* .. Array Arguments ..
DOUBLE PRECISION A( LDA, * )
* ..
*
* Purpose
* =======
*
* DLASET initializes an m-by-n matrix A to BETA on the diagonal and
* ALPHA on the offdiagonals.
*
* Arguments
* =========
*
* UPLO (input) CHARACTER*1
* Specifies the part of the matrix A to be set.
* = 'U': Upper triangular part is set; the strictly lower
* triangular part of A is not changed.
* = 'L': Lower triangular part is set; the strictly upper
* triangular part of A is not changed.
* Otherwise: All of the matrix A is set.
*
* M (input) INTEGER
* The number of rows of the matrix A. M >= 0.
*
* N (input) INTEGER
* The number of columns of the matrix A. N >= 0.
*
* ALPHA (input) DOUBLE PRECISION
* The constant to which the offdiagonal elements are to be set.
*
* BETA (input) DOUBLE PRECISION
* The constant to which the diagonal elements are to be set.
*
* A (input/output) DOUBLE PRECISION array, dimension (LDA,N)
* On exit, the leading m-by-n submatrix of A is set as follows:
*
* if UPLO = 'U', A(i,j) = ALPHA, 1<=i<=j-1, 1<=j<=n,
* if UPLO = 'L', A(i,j) = ALPHA, j+1<=i<=m, 1<=j<=n,
* otherwise, A(i,j) = ALPHA, 1<=i<=m, 1<=j<=n, i.ne.j,
*
* and, for all UPLO, A(i,i) = BETA, 1<=i<=min(m,n).
*
* LDA (input) INTEGER
* The leading dimension of the array A. LDA >= max(1,M).
*
* =====================================================================
*
* .. Local Scalars ..
INTEGER I, J
* ..
* .. External Functions ..
LOGICAL LSAME
EXTERNAL LSAME
* ..
* .. Intrinsic Functions ..
INTRINSIC MIN
* ..
* .. Executable Statements ..
*
IF( LSAME( UPLO, 'U' ) ) THEN
*
* Set the strictly upper triangular or trapezoidal part of the
* array to ALPHA.
*
DO 20 J = 2, N
DO 10 I = 1, MIN( J-1, M )
A( I, J ) = ALPHA
10 CONTINUE
20 CONTINUE
*
ELSE IF( LSAME( UPLO, 'L' ) ) THEN
*
* Set the strictly lower triangular or trapezoidal part of the
* array to ALPHA.
*
DO 40 J = 1, MIN( M, N )
DO 30 I = J + 1, M
A( I, J ) = ALPHA
30 CONTINUE
40 CONTINUE
*
ELSE
*
* Set the leading m-by-n submatrix to ALPHA.
*
DO 60 J = 1, N
DO 50 I = 1, M
A( I, J ) = ALPHA
50 CONTINUE
60 CONTINUE
END IF
*
* Set the first min(M,N) diagonal elements to BETA.
*
DO 70 I = 1, MIN( M, N )
A( I, I ) = BETA
70 CONTINUE
*
RETURN
*
* End of DLASET
*
END
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