LAPACK 3.3.1 Linear Algebra PACKage

# zlaset.f

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```00001       SUBROUTINE ZLASET( UPLO, M, N, ALPHA, BETA, A, LDA )
00002 *
00003 *  -- LAPACK auxiliary routine (version 3.2) --
00004 *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
00005 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00006 *     November 2006
00007 *
00008 *     .. Scalar Arguments ..
00009       CHARACTER          UPLO
00010       INTEGER            LDA, M, N
00011       COMPLEX*16         ALPHA, BETA
00012 *     ..
00013 *     .. Array Arguments ..
00014       COMPLEX*16         A( LDA, * )
00015 *     ..
00016 *
00017 *  Purpose
00018 *  =======
00019 *
00020 *  ZLASET initializes a 2-D array A to BETA on the diagonal and
00021 *  ALPHA on the offdiagonals.
00022 *
00023 *  Arguments
00024 *  =========
00025 *
00026 *  UPLO    (input) CHARACTER*1
00027 *          Specifies the part of the matrix A to be set.
00028 *          = 'U':      Upper triangular part is set. The lower triangle
00029 *                      is unchanged.
00030 *          = 'L':      Lower triangular part is set. The upper triangle
00031 *                      is unchanged.
00032 *          Otherwise:  All of the matrix A is set.
00033 *
00034 *  M       (input) INTEGER
00035 *          On entry, M specifies the number of rows of A.
00036 *
00037 *  N       (input) INTEGER
00038 *          On entry, N specifies the number of columns of A.
00039 *
00040 *  ALPHA   (input) COMPLEX*16
00041 *          All the offdiagonal array elements are set to ALPHA.
00042 *
00043 *  BETA    (input) COMPLEX*16
00044 *          All the diagonal array elements are set to BETA.
00045 *
00046 *  A       (input/output) COMPLEX*16 array, dimension (LDA,N)
00047 *          On entry, the m by n matrix A.
00048 *          On exit, A(i,j) = ALPHA, 1 <= i <= m, 1 <= j <= n, i.ne.j;
00049 *                   A(i,i) = BETA , 1 <= i <= min(m,n)
00050 *
00051 *  LDA     (input) INTEGER
00052 *          The leading dimension of the array A.  LDA >= max(1,M).
00053 *
00054 *  =====================================================================
00055 *
00056 *     .. Local Scalars ..
00057       INTEGER            I, J
00058 *     ..
00059 *     .. External Functions ..
00060       LOGICAL            LSAME
00061       EXTERNAL           LSAME
00062 *     ..
00063 *     .. Intrinsic Functions ..
00064       INTRINSIC          MIN
00065 *     ..
00066 *     .. Executable Statements ..
00067 *
00068       IF( LSAME( UPLO, 'U' ) ) THEN
00069 *
00070 *        Set the diagonal to BETA and the strictly upper triangular
00071 *        part of the array to ALPHA.
00072 *
00073          DO 20 J = 2, N
00074             DO 10 I = 1, MIN( J-1, M )
00075                A( I, J ) = ALPHA
00076    10       CONTINUE
00077    20    CONTINUE
00078          DO 30 I = 1, MIN( N, M )
00079             A( I, I ) = BETA
00080    30    CONTINUE
00081 *
00082       ELSE IF( LSAME( UPLO, 'L' ) ) THEN
00083 *
00084 *        Set the diagonal to BETA and the strictly lower triangular
00085 *        part of the array to ALPHA.
00086 *
00087          DO 50 J = 1, MIN( M, N )
00088             DO 40 I = J + 1, M
00089                A( I, J ) = ALPHA
00090    40       CONTINUE
00091    50    CONTINUE
00092          DO 60 I = 1, MIN( N, M )
00093             A( I, I ) = BETA
00094    60    CONTINUE
00095 *
00096       ELSE
00097 *
00098 *        Set the array to BETA on the diagonal and ALPHA on the
00099 *        offdiagonal.
00100 *
00101          DO 80 J = 1, N
00102             DO 70 I = 1, M
00103                A( I, J ) = ALPHA
00104    70       CONTINUE
00105    80    CONTINUE
00106          DO 90 I = 1, MIN( M, N )
00107             A( I, I ) = BETA
00108    90    CONTINUE
00109       END IF
00110 *
00111       RETURN
00112 *
00113 *     End of ZLASET
00114 *
00115       END
```