1: SUBROUTINE DLASET( UPLO, M, N, ALPHA, BETA, A, LDA )
2: *
3: * -- LAPACK auxiliary routine (version 3.2) --
4: * -- LAPACK is a software package provided by Univ. of Tennessee, --
5: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
6: * November 2006
7: *
8: * .. Scalar Arguments ..
9: CHARACTER UPLO
10: INTEGER LDA, M, N
11: DOUBLE PRECISION ALPHA, BETA
12: * ..
13: * .. Array Arguments ..
14: DOUBLE PRECISION A( LDA, * )
15: * ..
16: *
17: * Purpose
18: * =======
19: *
20: * DLASET initializes an m-by-n matrix A to BETA on the diagonal and
21: * ALPHA on the offdiagonals.
22: *
23: * Arguments
24: * =========
25: *
26: * UPLO (input) CHARACTER*1
27: * Specifies the part of the matrix A to be set.
28: * = 'U': Upper triangular part is set; the strictly lower
29: * triangular part of A is not changed.
30: * = 'L': Lower triangular part is set; the strictly upper
31: * triangular part of A is not changed.
32: * Otherwise: All of the matrix A is set.
33: *
34: * M (input) INTEGER
35: * The number of rows of the matrix A. M >= 0.
36: *
37: * N (input) INTEGER
38: * The number of columns of the matrix A. N >= 0.
39: *
40: * ALPHA (input) DOUBLE PRECISION
41: * The constant to which the offdiagonal elements are to be set.
42: *
43: * BETA (input) DOUBLE PRECISION
44: * The constant to which the diagonal elements are to be set.
45: *
46: * A (input/output) DOUBLE PRECISION array, dimension (LDA,N)
47: * On exit, the leading m-by-n submatrix of A is set as follows:
48: *
49: * if UPLO = 'U', A(i,j) = ALPHA, 1<=i<=j-1, 1<=j<=n,
50: * if UPLO = 'L', A(i,j) = ALPHA, j+1<=i<=m, 1<=j<=n,
51: * otherwise, A(i,j) = ALPHA, 1<=i<=m, 1<=j<=n, i.ne.j,
52: *
53: * and, for all UPLO, A(i,i) = BETA, 1<=i<=min(m,n).
54: *
55: * LDA (input) INTEGER
56: * The leading dimension of the array A. LDA >= max(1,M).
57: *
58: * =====================================================================
59: *
60: * .. Local Scalars ..
61: INTEGER I, J
62: * ..
63: * .. External Functions ..
64: LOGICAL LSAME
65: EXTERNAL LSAME
66: * ..
67: * .. Intrinsic Functions ..
68: INTRINSIC MIN
69: * ..
70: * .. Executable Statements ..
71: *
72: IF( LSAME( UPLO, 'U' ) ) THEN
73: *
74: * Set the strictly upper triangular or trapezoidal part of the
75: * array to ALPHA.
76: *
77: DO 20 J = 2, N
78: DO 10 I = 1, MIN( J-1, M )
79: A( I, J ) = ALPHA
80: 10 CONTINUE
81: 20 CONTINUE
82: *
83: ELSE IF( LSAME( UPLO, 'L' ) ) THEN
84: *
85: * Set the strictly lower triangular or trapezoidal part of the
86: * array to ALPHA.
87: *
88: DO 40 J = 1, MIN( M, N )
89: DO 30 I = J + 1, M
90: A( I, J ) = ALPHA
91: 30 CONTINUE
92: 40 CONTINUE
93: *
94: ELSE
95: *
96: * Set the leading m-by-n submatrix to ALPHA.
97: *
98: DO 60 J = 1, N
99: DO 50 I = 1, M
100: A( I, J ) = ALPHA
101: 50 CONTINUE
102: 60 CONTINUE
103: END IF
104: *
105: * Set the first min(M,N) diagonal elements to BETA.
106: *
107: DO 70 I = 1, MIN( M, N )
108: A( I, I ) = BETA
109: 70 CONTINUE
110: *
111: RETURN
112: *
113: * End of DLASET
114: *
115: END
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