slaset()

subroutine slaset	(	character	uplo,
		integer	m,
		integer	n,
		real	alpha,
		real	beta,
		real, dimension( lda, * )	a,
		integer	lda
	)

SLASET initializes the off-diagonal elements and the diagonal elements of a matrix to given values.

Download SLASET + dependencies [TGZ] [ZIP] [TXT]

Purpose:

 SLASET initializes an m-by-n matrix A to BETA on the diagonal and
 ALPHA on the offdiagonals.

Parameters

[in]	UPLO	UPLO is 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.
[in]	M	M is INTEGER The number of rows of the matrix A. M >= 0.
[in]	N	N is INTEGER The number of columns of the matrix A. N >= 0.
[in]	ALPHA	ALPHA is REAL The constant to which the offdiagonal elements are to be set.
[in]	BETA	BETA is REAL The constant to which the diagonal elements are to be set.
[out]	A	A is REAL 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).
[in]	LDA	LDA is INTEGER The leading dimension of the array A. LDA >= max(1,M).

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 109 of file slaset.f.

*
*  -- LAPACK auxiliary routine --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*
*     .. Scalar Arguments ..
      CHARACTER          UPLO
      INTEGER            LDA, M, N
      REAL               ALPHA, BETA
*     ..
*     .. Array Arguments ..
      REAL               A( LDA, * )
*     ..
*
* =====================================================================
*
*     .. 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 SLASET
*