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1 SUBROUTINE DLASET( UPLO, M, N, ALPHA, BETA, A, LDA ) |
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2 * |
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7034
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3 * -- LAPACK auxiliary routine (version 3.1) -- |
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4 * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. |
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5 * November 2006 |
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6 * |
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7 * .. Scalar Arguments .. |
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8 CHARACTER UPLO |
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9 INTEGER LDA, M, N |
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10 DOUBLE PRECISION ALPHA, BETA |
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11 * .. |
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12 * .. Array Arguments .. |
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13 DOUBLE PRECISION A( LDA, * ) |
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14 * .. |
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15 * |
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16 * Purpose |
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17 * ======= |
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18 * |
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19 * DLASET initializes an m-by-n matrix A to BETA on the diagonal and |
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20 * ALPHA on the offdiagonals. |
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21 * |
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22 * Arguments |
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23 * ========= |
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24 * |
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25 * UPLO (input) CHARACTER*1 |
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26 * Specifies the part of the matrix A to be set. |
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27 * = 'U': Upper triangular part is set; the strictly lower |
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28 * triangular part of A is not changed. |
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29 * = 'L': Lower triangular part is set; the strictly upper |
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30 * triangular part of A is not changed. |
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31 * Otherwise: All of the matrix A is set. |
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32 * |
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33 * M (input) INTEGER |
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34 * The number of rows of the matrix A. M >= 0. |
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35 * |
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36 * N (input) INTEGER |
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37 * The number of columns of the matrix A. N >= 0. |
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38 * |
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39 * ALPHA (input) DOUBLE PRECISION |
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40 * The constant to which the offdiagonal elements are to be set. |
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41 * |
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42 * BETA (input) DOUBLE PRECISION |
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43 * The constant to which the diagonal elements are to be set. |
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44 * |
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45 * A (input/output) DOUBLE PRECISION array, dimension (LDA,N) |
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46 * On exit, the leading m-by-n submatrix of A is set as follows: |
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47 * |
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48 * if UPLO = 'U', A(i,j) = ALPHA, 1<=i<=j-1, 1<=j<=n, |
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49 * if UPLO = 'L', A(i,j) = ALPHA, j+1<=i<=m, 1<=j<=n, |
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50 * otherwise, A(i,j) = ALPHA, 1<=i<=m, 1<=j<=n, i.ne.j, |
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51 * |
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52 * and, for all UPLO, A(i,i) = BETA, 1<=i<=min(m,n). |
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53 * |
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54 * LDA (input) INTEGER |
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55 * The leading dimension of the array A. LDA >= max(1,M). |
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56 * |
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57 * ===================================================================== |
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58 * |
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59 * .. Local Scalars .. |
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60 INTEGER I, J |
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61 * .. |
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62 * .. External Functions .. |
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63 LOGICAL LSAME |
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64 EXTERNAL LSAME |
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65 * .. |
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66 * .. Intrinsic Functions .. |
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67 INTRINSIC MIN |
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68 * .. |
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69 * .. Executable Statements .. |
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70 * |
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71 IF( LSAME( UPLO, 'U' ) ) THEN |
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72 * |
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73 * Set the strictly upper triangular or trapezoidal part of the |
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74 * array to ALPHA. |
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75 * |
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76 DO 20 J = 2, N |
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77 DO 10 I = 1, MIN( J-1, M ) |
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78 A( I, J ) = ALPHA |
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79 10 CONTINUE |
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80 20 CONTINUE |
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81 * |
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82 ELSE IF( LSAME( UPLO, 'L' ) ) THEN |
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83 * |
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84 * Set the strictly lower triangular or trapezoidal part of the |
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85 * array to ALPHA. |
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86 * |
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87 DO 40 J = 1, MIN( M, N ) |
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88 DO 30 I = J + 1, M |
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89 A( I, J ) = ALPHA |
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90 30 CONTINUE |
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91 40 CONTINUE |
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92 * |
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93 ELSE |
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94 * |
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95 * Set the leading m-by-n submatrix to ALPHA. |
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96 * |
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97 DO 60 J = 1, N |
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98 DO 50 I = 1, M |
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99 A( I, J ) = ALPHA |
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100 50 CONTINUE |
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101 60 CONTINUE |
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102 END IF |
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103 * |
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104 * Set the first min(M,N) diagonal elements to BETA. |
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105 * |
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106 DO 70 I = 1, MIN( M, N ) |
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107 A( I, I ) = BETA |
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108 70 CONTINUE |
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109 * |
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110 RETURN |
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111 * |
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112 * End of DLASET |
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113 * |
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114 END |
