LAPACK  3.10.1 LAPACK: Linear Algebra PACKage
zgeru.f
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1 *> \brief \b ZGERU
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 ZGERU(M,N,ALPHA,X,INCX,Y,INCY,A,LDA)
12 *
13 * .. Scalar Arguments ..
14 * COMPLEX*16 ALPHA
15 * INTEGER INCX,INCY,LDA,M,N
16 * ..
17 * .. Array Arguments ..
18 * COMPLEX*16 A(LDA,*),X(*),Y(*)
19 * ..
20 *
21 *
22 *> \par Purpose:
23 * =============
24 *>
25 *> \verbatim
26 *>
27 *> ZGERU 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 COMPLEX*16
55 *> On entry, ALPHA specifies the scalar alpha.
56 *> \endverbatim
57 *>
58 *> \param[in] X
59 *> \verbatim
60 *> X is COMPLEX*16 array, 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 COMPLEX*16 array, 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 COMPLEX*16 array, 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 *> \ingroup complex16_blas_level2
113 *
114 *> \par Further Details:
115 * =====================
116 *>
117 *> \verbatim
118 *>
119 *> Level 2 Blas routine.
120 *>
121 *> -- Written on 22-October-1986.
122 *> Jack Dongarra, Argonne National Lab.
123 *> Jeremy Du Croz, Nag Central Office.
124 *> Sven Hammarling, Nag Central Office.
125 *> Richard Hanson, Sandia National Labs.
126 *> \endverbatim
127 *>
128 * =====================================================================
129  SUBROUTINE zgeru(M,N,ALPHA,X,INCX,Y,INCY,A,LDA)
130 *
131 * -- Reference BLAS level2 routine --
132 * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
133 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
134 *
135 * .. Scalar Arguments ..
136  COMPLEX*16 ALPHA
137  INTEGER INCX,INCY,LDA,M,N
138 * ..
139 * .. Array Arguments ..
140  COMPLEX*16 A(LDA,*),X(*),Y(*)
141 * ..
142 *
143 * =====================================================================
144 *
145 * .. Parameters ..
146  COMPLEX*16 ZERO
147  parameter(zero= (0.0d+0,0.0d+0))
148 * ..
149 * .. Local Scalars ..
150  COMPLEX*16 TEMP
151  INTEGER I,INFO,IX,J,JY,KX
152 * ..
153 * .. External Subroutines ..
154  EXTERNAL xerbla
155 * ..
156 * .. Intrinsic Functions ..
157  INTRINSIC max
158 * ..
159 *
160 * Test the input parameters.
161 *
162  info = 0
163  IF (m.LT.0) THEN
164  info = 1
165  ELSE IF (n.LT.0) THEN
166  info = 2
167  ELSE IF (incx.EQ.0) THEN
168  info = 5
169  ELSE IF (incy.EQ.0) THEN
170  info = 7
171  ELSE IF (lda.LT.max(1,m)) THEN
172  info = 9
173  END IF
174  IF (info.NE.0) THEN
175  CALL xerbla('ZGERU ',info)
176  RETURN
177  END IF
178 *
179 * Quick return if possible.
180 *
181  IF ((m.EQ.0) .OR. (n.EQ.0) .OR. (alpha.EQ.zero)) RETURN
182 *
183 * Start the operations. In this version the elements of A are
184 * accessed sequentially with one pass through A.
185 *
186  IF (incy.GT.0) THEN
187  jy = 1
188  ELSE
189  jy = 1 - (n-1)*incy
190  END IF
191  IF (incx.EQ.1) THEN
192  DO 20 j = 1,n
193  IF (y(jy).NE.zero) THEN
194  temp = alpha*y(jy)
195  DO 10 i = 1,m
196  a(i,j) = a(i,j) + x(i)*temp
197  10 CONTINUE
198  END IF
199  jy = jy + incy
200  20 CONTINUE
201  ELSE
202  IF (incx.GT.0) THEN
203  kx = 1
204  ELSE
205  kx = 1 - (m-1)*incx
206  END IF
207  DO 40 j = 1,n
208  IF (y(jy).NE.zero) THEN
209  temp = alpha*y(jy)
210  ix = kx
211  DO 30 i = 1,m
212  a(i,j) = a(i,j) + x(ix)*temp
213  ix = ix + incx
214  30 CONTINUE
215  END IF
216  jy = jy + incy
217  40 CONTINUE
218  END IF
219 *
220  RETURN
221 *
222 * End of ZGERU
223 *
224  END
subroutine xerbla(SRNAME, INFO)
XERBLA
Definition: xerbla.f:60
subroutine zgeru(M, N, ALPHA, X, INCX, Y, INCY, A, LDA)
ZGERU
Definition: zgeru.f:130