| 1 | SUBROUTINE CGERC(M,N,ALPHA,X,INCX,Y,INCY,A,LDA) |
|---|
| 2 | * .. Scalar Arguments .. |
|---|
| 3 | COMPLEX ALPHA |
|---|
| 4 | INTEGER INCX,INCY,LDA,M,N |
|---|
| 5 | * .. |
|---|
| 6 | * .. Array Arguments .. |
|---|
| 7 | COMPLEX A(LDA,*),X(*),Y(*) |
|---|
| 8 | * .. |
|---|
| 9 | * |
|---|
| 10 | * Purpose |
|---|
| 11 | * ======= |
|---|
| 12 | * |
|---|
| 13 | * CGERC performs the rank 1 operation |
|---|
| 14 | * |
|---|
| 15 | * A := alpha*x*conjg( y' ) + A, |
|---|
| 16 | * |
|---|
| 17 | * where alpha is a scalar, x is an m element vector, y is an n element |
|---|
| 18 | * vector and A is an m by n matrix. |
|---|
| 19 | * |
|---|
| 20 | * Arguments |
|---|
| 21 | * ========== |
|---|
| 22 | * |
|---|
| 23 | * M - INTEGER. |
|---|
| 24 | * On entry, M specifies the number of rows of the matrix A. |
|---|
| 25 | * M must be at least zero. |
|---|
| 26 | * Unchanged on exit. |
|---|
| 27 | * |
|---|
| 28 | * N - INTEGER. |
|---|
| 29 | * On entry, N specifies the number of columns of the matrix A. |
|---|
| 30 | * N must be at least zero. |
|---|
| 31 | * Unchanged on exit. |
|---|
| 32 | * |
|---|
| 33 | * ALPHA - COMPLEX . |
|---|
| 34 | * On entry, ALPHA specifies the scalar alpha. |
|---|
| 35 | * Unchanged on exit. |
|---|
| 36 | * |
|---|
| 37 | * X - COMPLEX array of dimension at least |
|---|
| 38 | * ( 1 + ( m - 1 )*abs( INCX ) ). |
|---|
| 39 | * Before entry, the incremented array X must contain the m |
|---|
| 40 | * element vector x. |
|---|
| 41 | * Unchanged on exit. |
|---|
| 42 | * |
|---|
| 43 | * INCX - INTEGER. |
|---|
| 44 | * On entry, INCX specifies the increment for the elements of |
|---|
| 45 | * X. INCX must not be zero. |
|---|
| 46 | * Unchanged on exit. |
|---|
| 47 | * |
|---|
| 48 | * Y - COMPLEX array of dimension at least |
|---|
| 49 | * ( 1 + ( n - 1 )*abs( INCY ) ). |
|---|
| 50 | * Before entry, the incremented array Y must contain the n |
|---|
| 51 | * element vector y. |
|---|
| 52 | * Unchanged on exit. |
|---|
| 53 | * |
|---|
| 54 | * INCY - INTEGER. |
|---|
| 55 | * On entry, INCY specifies the increment for the elements of |
|---|
| 56 | * Y. INCY must not be zero. |
|---|
| 57 | * Unchanged on exit. |
|---|
| 58 | * |
|---|
| 59 | * A - COMPLEX array of DIMENSION ( LDA, n ). |
|---|
| 60 | * Before entry, the leading m by n part of the array A must |
|---|
| 61 | * contain the matrix of coefficients. On exit, A is |
|---|
| 62 | * overwritten by the updated matrix. |
|---|
| 63 | * |
|---|
| 64 | * LDA - INTEGER. |
|---|
| 65 | * On entry, LDA specifies the first dimension of A as declared |
|---|
| 66 | * in the calling (sub) program. LDA must be at least |
|---|
| 67 | * max( 1, m ). |
|---|
| 68 | * Unchanged on exit. |
|---|
| 69 | * |
|---|
| 70 | * |
|---|
| 71 | * Level 2 Blas routine. |
|---|
| 72 | * |
|---|
| 73 | * -- Written on 22-October-1986. |
|---|
| 74 | * Jack Dongarra, Argonne National Lab. |
|---|
| 75 | * Jeremy Du Croz, Nag Central Office. |
|---|
| 76 | * Sven Hammarling, Nag Central Office. |
|---|
| 77 | * Richard Hanson, Sandia National Labs. |
|---|
| 78 | * |
|---|
| 79 | * |
|---|
| 80 | * .. Parameters .. |
|---|
| 81 | COMPLEX ZERO |
|---|
| 82 | PARAMETER (ZERO= (0.0E+0,0.0E+0)) |
|---|
| 83 | * .. |
|---|
| 84 | * .. Local Scalars .. |
|---|
| 85 | COMPLEX TEMP |
|---|
| 86 | INTEGER I,INFO,IX,J,JY,KX |
|---|
| 87 | * .. |
|---|
| 88 | * .. External Subroutines .. |
|---|
| 89 | EXTERNAL XERBLA |
|---|
| 90 | * .. |
|---|
| 91 | * .. Intrinsic Functions .. |
|---|
| 92 | INTRINSIC CONJG,MAX |
|---|
| 93 | * .. |
|---|
| 94 | * |
|---|
| 95 | * Test the input parameters. |
|---|
| 96 | * |
|---|
| 97 | INFO = 0 |
|---|
| 98 | IF (M.LT.0) THEN |
|---|
| 99 | INFO = 1 |
|---|
| 100 | ELSE IF (N.LT.0) THEN |
|---|
| 101 | INFO = 2 |
|---|
| 102 | ELSE IF (INCX.EQ.0) THEN |
|---|
| 103 | INFO = 5 |
|---|
| 104 | ELSE IF (INCY.EQ.0) THEN |
|---|
| 105 | INFO = 7 |
|---|
| 106 | ELSE IF (LDA.LT.MAX(1,M)) THEN |
|---|
| 107 | INFO = 9 |
|---|
| 108 | END IF |
|---|
| 109 | IF (INFO.NE.0) THEN |
|---|
| 110 | CALL XERBLA('CGERC ',INFO) |
|---|
| 111 | RETURN |
|---|
| 112 | END IF |
|---|
| 113 | * |
|---|
| 114 | * Quick return if possible. |
|---|
| 115 | * |
|---|
| 116 | IF ((M.EQ.0) .OR. (N.EQ.0) .OR. (ALPHA.EQ.ZERO)) RETURN |
|---|
| 117 | * |
|---|
| 118 | * Start the operations. In this version the elements of A are |
|---|
| 119 | * accessed sequentially with one pass through A. |
|---|
| 120 | * |
|---|
| 121 | IF (INCY.GT.0) THEN |
|---|
| 122 | JY = 1 |
|---|
| 123 | ELSE |
|---|
| 124 | JY = 1 - (N-1)*INCY |
|---|
| 125 | END IF |
|---|
| 126 | IF (INCX.EQ.1) THEN |
|---|
| 127 | DO 20 J = 1,N |
|---|
| 128 | IF (Y(JY).NE.ZERO) THEN |
|---|
| 129 | TEMP = ALPHA*CONJG(Y(JY)) |
|---|
| 130 | DO 10 I = 1,M |
|---|
| 131 | A(I,J) = A(I,J) + X(I)*TEMP |
|---|
| 132 | 10 CONTINUE |
|---|
| 133 | END IF |
|---|
| 134 | JY = JY + INCY |
|---|
| 135 | 20 CONTINUE |
|---|
| 136 | ELSE |
|---|
| 137 | IF (INCX.GT.0) THEN |
|---|
| 138 | KX = 1 |
|---|
| 139 | ELSE |
|---|
| 140 | KX = 1 - (M-1)*INCX |
|---|
| 141 | END IF |
|---|
| 142 | DO 40 J = 1,N |
|---|
| 143 | IF (Y(JY).NE.ZERO) THEN |
|---|
| 144 | TEMP = ALPHA*CONJG(Y(JY)) |
|---|
| 145 | IX = KX |
|---|
| 146 | DO 30 I = 1,M |
|---|
| 147 | A(I,J) = A(I,J) + X(IX)*TEMP |
|---|
| 148 | IX = IX + INCX |
|---|
| 149 | 30 CONTINUE |
|---|
| 150 | END IF |
|---|
| 151 | JY = JY + INCY |
|---|
| 152 | 40 CONTINUE |
|---|
| 153 | END IF |
|---|
| 154 | * |
|---|
| 155 | RETURN |
|---|
| 156 | * |
|---|
| 157 | * End of CGERC . |
|---|
| 158 | * |
|---|
| 159 | END |
|---|
