Annotation of rpl/lapack/blas/dger.f, revision 1.12
1.8 bertrand 1: *> \brief \b DGER
2: *
3: * =========== DOCUMENTATION ===========
4: *
5: * Online html documentation available at
6: * http://www.netlib.org/lapack/explore-html/
7: *
8: * Definition:
9: * ===========
10: *
11: * SUBROUTINE DGER(M,N,ALPHA,X,INCX,Y,INCY,A,LDA)
12: *
13: * .. Scalar Arguments ..
14: * DOUBLE PRECISION ALPHA
15: * INTEGER INCX,INCY,LDA,M,N
16: * ..
17: * .. Array Arguments ..
18: * DOUBLE PRECISION A(LDA,*),X(*),Y(*)
19: * ..
20: *
21: *
22: *> \par Purpose:
23: * =============
24: *>
25: *> \verbatim
26: *>
27: *> DGER performs the rank 1 operation
28: *>
29: *> A := alpha*x*y**T + A,
30: *>
31: *> where alpha is a scalar, x is an m element vector, y is an n element
32: *> vector and A is an m by n matrix.
33: *> \endverbatim
34: *
35: * Arguments:
36: * ==========
37: *
38: *> \param[in] M
39: *> \verbatim
40: *> M is INTEGER
41: *> On entry, M specifies the number of rows of the matrix A.
42: *> M must be at least zero.
43: *> \endverbatim
44: *>
45: *> \param[in] N
46: *> \verbatim
47: *> N is INTEGER
48: *> On entry, N specifies the number of columns of the matrix A.
49: *> N must be at least zero.
50: *> \endverbatim
51: *>
52: *> \param[in] ALPHA
53: *> \verbatim
54: *> ALPHA is DOUBLE PRECISION.
55: *> On entry, ALPHA specifies the scalar alpha.
56: *> \endverbatim
57: *>
58: *> \param[in] X
59: *> \verbatim
60: *> X is DOUBLE PRECISION array of dimension at least
61: *> ( 1 + ( m - 1 )*abs( INCX ) ).
62: *> Before entry, the incremented array X must contain the m
63: *> element vector x.
64: *> \endverbatim
65: *>
66: *> \param[in] INCX
67: *> \verbatim
68: *> INCX is INTEGER
69: *> On entry, INCX specifies the increment for the elements of
70: *> X. INCX must not be zero.
71: *> \endverbatim
72: *>
73: *> \param[in] Y
74: *> \verbatim
75: *> Y is DOUBLE PRECISION array of dimension at least
76: *> ( 1 + ( n - 1 )*abs( INCY ) ).
77: *> Before entry, the incremented array Y must contain the n
78: *> element vector y.
79: *> \endverbatim
80: *>
81: *> \param[in] INCY
82: *> \verbatim
83: *> INCY is INTEGER
84: *> On entry, INCY specifies the increment for the elements of
85: *> Y. INCY must not be zero.
86: *> \endverbatim
87: *>
88: *> \param[in,out] A
89: *> \verbatim
90: *> A is DOUBLE PRECISION array of DIMENSION ( LDA, n ).
91: *> Before entry, the leading m by n part of the array A must
92: *> contain the matrix of coefficients. On exit, A is
93: *> overwritten by the updated matrix.
94: *> \endverbatim
95: *>
96: *> \param[in] LDA
97: *> \verbatim
98: *> LDA is INTEGER
99: *> On entry, LDA specifies the first dimension of A as declared
100: *> in the calling (sub) program. LDA must be at least
101: *> max( 1, m ).
102: *> \endverbatim
103: *
104: * Authors:
105: * ========
106: *
107: *> \author Univ. of Tennessee
108: *> \author Univ. of California Berkeley
109: *> \author Univ. of Colorado Denver
110: *> \author NAG Ltd.
111: *
112: *> \date November 2011
113: *
114: *> \ingroup double_blas_level2
115: *
116: *> \par Further Details:
117: * =====================
118: *>
119: *> \verbatim
120: *>
121: *> Level 2 Blas routine.
122: *>
123: *> -- Written on 22-October-1986.
124: *> Jack Dongarra, Argonne National Lab.
125: *> Jeremy Du Croz, Nag Central Office.
126: *> Sven Hammarling, Nag Central Office.
127: *> Richard Hanson, Sandia National Labs.
128: *> \endverbatim
129: *>
130: * =====================================================================
1.1 bertrand 131: SUBROUTINE DGER(M,N,ALPHA,X,INCX,Y,INCY,A,LDA)
1.8 bertrand 132: *
133: * -- Reference BLAS level2 routine (version 3.4.0) --
134: * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
135: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
136: * November 2011
137: *
1.1 bertrand 138: * .. Scalar Arguments ..
139: DOUBLE PRECISION ALPHA
140: INTEGER INCX,INCY,LDA,M,N
141: * ..
142: * .. Array Arguments ..
143: DOUBLE PRECISION A(LDA,*),X(*),Y(*)
144: * ..
145: *
146: * =====================================================================
147: *
148: * .. Parameters ..
149: DOUBLE PRECISION ZERO
150: PARAMETER (ZERO=0.0D+0)
151: * ..
152: * .. Local Scalars ..
153: DOUBLE PRECISION TEMP
154: INTEGER I,INFO,IX,J,JY,KX
155: * ..
156: * .. External Subroutines ..
157: EXTERNAL XERBLA
158: * ..
159: * .. Intrinsic Functions ..
160: INTRINSIC MAX
161: * ..
162: *
163: * Test the input parameters.
164: *
165: INFO = 0
166: IF (M.LT.0) THEN
167: INFO = 1
168: ELSE IF (N.LT.0) THEN
169: INFO = 2
170: ELSE IF (INCX.EQ.0) THEN
171: INFO = 5
172: ELSE IF (INCY.EQ.0) THEN
173: INFO = 7
174: ELSE IF (LDA.LT.MAX(1,M)) THEN
175: INFO = 9
176: END IF
177: IF (INFO.NE.0) THEN
178: CALL XERBLA('DGER ',INFO)
179: RETURN
180: END IF
181: *
182: * Quick return if possible.
183: *
184: IF ((M.EQ.0) .OR. (N.EQ.0) .OR. (ALPHA.EQ.ZERO)) RETURN
185: *
186: * Start the operations. In this version the elements of A are
187: * accessed sequentially with one pass through A.
188: *
189: IF (INCY.GT.0) THEN
190: JY = 1
191: ELSE
192: JY = 1 - (N-1)*INCY
193: END IF
194: IF (INCX.EQ.1) THEN
195: DO 20 J = 1,N
196: IF (Y(JY).NE.ZERO) THEN
197: TEMP = ALPHA*Y(JY)
198: DO 10 I = 1,M
199: A(I,J) = A(I,J) + X(I)*TEMP
200: 10 CONTINUE
201: END IF
202: JY = JY + INCY
203: 20 CONTINUE
204: ELSE
205: IF (INCX.GT.0) THEN
206: KX = 1
207: ELSE
208: KX = 1 - (M-1)*INCX
209: END IF
210: DO 40 J = 1,N
211: IF (Y(JY).NE.ZERO) THEN
212: TEMP = ALPHA*Y(JY)
213: IX = KX
214: DO 30 I = 1,M
215: A(I,J) = A(I,J) + X(IX)*TEMP
216: IX = IX + INCX
217: 30 CONTINUE
218: END IF
219: JY = JY + INCY
220: 40 CONTINUE
221: END IF
222: *
223: RETURN
224: *
225: * End of DGER .
226: *
227: END
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