SCALAPACK 2.2.2
LAPACK: Linear Algebra PACKage
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◆ pbdvecadd()

subroutine pbdvecadd ( integer  icontxt,
character*1  mode,
integer  n,
double precision  alpha,
double precision, dimension( * )  x,
integer  incx,
double precision  beta,
double precision, dimension( * )  y,
integer  incy 
)

Definition at line 1 of file pbdvecadd.f.

3*
4* -- PB-BLAS routine (version 2.1) --
5* University of Tennessee, Knoxville, Oak Ridge National Laboratory.
6* April 28, 1996
7*
8* .. Scalar Arguments ..
9 CHARACTER*1 MODE
10 INTEGER ICONTXT, INCX, INCY, N
11 DOUBLE PRECISION ALPHA, BETA
12* ..
13* .. Array Arguments ..
14 DOUBLE PRECISION X( * ), Y( * )
15*
16* ..
17*
18* Purpose
19* =======
20*
21* PBDVECADD performs a vector X to be added to Y
22* Y := alpha*op(X) + beta*Y,
23* where alpha and beta are scalars, and X and Y are n vectors,
24* and op(X) = X**H if MODE = 'C',
25*
26* Arguments
27* =========
28*
29* ICONTXT (input) INTEGER
30* ICONTXT is the BLACS mechanism for partitioning communication
31* space. A defining property of a context is that a message in
32* a context cannot be sent or received in another context. The
33* BLACS context includes the definition of a grid, and each
34* process' coordinates in it.
35*
36* MODE (input) CHARACTER*1
37* Specifies the transposed, or conjugate transposed vector X
38* to be added to the vector Y
39* = 'C': Conjugate vector X is added for complex data set.
40* Y = alpha * X**H + beta * Y
41* ELSE : Vector X is added. Y = alpha*X + beta*Y
42* if MODE = 'V', BLAS routine may be used.
43*
44* N (input) INTEGER
45* The number of elements of the vectors X and Y to be added.
46* N >= 0.
47*
48* ALPHA (input) DOUBLE PRECISION
49* ALPHA specifies the scalar alpha.
50*
51* X (input) DOUBLE PRECISION array of DIMENSION at least
52* ( 1 + ( N - 1 )*abs( INCX ) )
53* The incremented array X must contain the vector X.
54*
55* INCX (input) INTEGER
56* INCX specifies the increment for the elements of X.
57* INCX <> 0.
58*
59* BETA (input) DOUBLE PRECISION
60* BETA specifies the scalar beta.
61*
62* Y (input/output) DOUBLE PRECISION array of DIMENSION at least
63* ( 1 + ( N - 1 )*abs( INCY ) )
64* On entry with BETA non-zero, the incremented array Y must
65* contain the vector Y.
66* On exit, Y is overwritten by the updated vector Y.
67*
68* INCY - (input) INTEGER
69* INCY specifies the increment for the elements of Y.
70* INCY <> 0.
71*
72* =====================================================================
73*
74* ..
75* .. Parameters ..
76 DOUBLE PRECISION ZERO, ONE
77 parameter( zero = 0.0d+0, one = 1.0d+0)
78* ..
79* .. Local Scalars ..
80 INTEGER I, IX, IY
81* ..
82* .. External Functions ..
83 LOGICAL LSAME
84 EXTERNAL lsame
85* ..
86* .. External Subroutines ..
87 EXTERNAL dscal, dcopy, daxpy
88* ..
89* .. Executable Statements ..
90*
91 IF( n.LE.0 .OR. ( alpha.EQ.zero .AND. beta.EQ.one ) ) RETURN
92*
93 IF( alpha.EQ.zero ) THEN
94 IF( beta.EQ.zero ) THEN
95 IF( incy.EQ.1 ) THEN
96 DO 10 i = 1, n
97 y( i ) = zero
98 10 CONTINUE
99 ELSE
100 iy = 1
101 DO 20 i = 1, n
102 y( iy ) = zero
103 iy = iy + incy
104 20 CONTINUE
105 END IF
106*
107 ELSE
108 IF( lsame( mode, 'V' ) ) THEN
109 CALL dscal( n, beta, y, incy )
110 ELSE IF( incy.EQ.1 ) THEN
111 DO 30 i = 1, n
112 y( i ) = beta * y( i )
113 30 CONTINUE
114 ELSE
115 iy = 1
116 DO 40 i = 1, n
117 y( iy ) = beta * y( iy )
118 iy = iy + incy
119 40 CONTINUE
120 END IF
121 END IF
122*
123 ELSE
124 IF( alpha.EQ.one ) THEN
125 IF( beta.EQ.zero ) THEN
126 IF( lsame( mode, 'V' ) ) THEN
127 CALL dcopy( n, x, incx, y, incy )
128 ELSE IF( incx.EQ.1 .AND. incy.EQ.1 ) THEN
129 DO 50 i = 1, n
130 y( i ) = x( i )
131 50 CONTINUE
132 ELSE
133 ix = 1
134 iy = 1
135 DO 60 i = 1, n
136 y( iy ) = x( ix )
137 ix = ix + incx
138 iy = iy + incy
139 60 CONTINUE
140 END IF
141*
142 ELSE IF( beta.EQ.one ) THEN
143 IF( incx.EQ.1 .AND. incy.EQ.1 ) THEN
144 DO 70 i = 1, n
145 y( i ) = x( i ) + y( i )
146 70 CONTINUE
147 ELSE
148 ix = 1
149 iy = 1
150 DO 80 i = 1, n
151 y( iy ) = x( ix ) + y( iy )
152 ix = ix + incx
153 iy = iy + incy
154 80 CONTINUE
155 END IF
156*
157 ELSE
158 IF( incx.EQ.1 .AND. incy.EQ.1 ) THEN
159 DO 90 i = 1, n
160 y( i ) = x( i ) + beta * y( i )
161 90 CONTINUE
162 ELSE
163 ix = 1
164 iy = 1
165 DO 100 i = 1, n
166 y( iy ) = x( ix ) + beta * y( iy )
167 ix = ix + incx
168 iy = iy + incy
169 100 CONTINUE
170 END IF
171 END IF
172*
173 ELSE
174 IF( beta.EQ.zero ) THEN
175 IF( incx.EQ.1 .AND. incy.EQ.1 ) THEN
176 DO 110 i = 1, n
177 y( i ) = alpha * x( i )
178 110 CONTINUE
179 ELSE
180 ix = 1
181 iy = 1
182 DO 120 i = 1, n
183 y( iy ) = x( ix )
184 ix = ix + incx
185 iy = iy + incy
186 120 CONTINUE
187 END IF
188*
189 ELSE IF( beta.EQ.one ) THEN
190 IF( lsame( mode, 'V' ) ) THEN
191 CALL daxpy( n, alpha, x, incx, y, incy )
192 ELSE IF( incx.EQ.1 .AND. incy.EQ.1 ) THEN
193 DO 130 i = 1, n
194 y( i ) = alpha * x( i ) + y( i )
195 130 CONTINUE
196 ELSE
197 ix = 1
198 iy = 1
199 DO 140 i = 1, n
200 y( iy ) = alpha * x( ix ) + y( iy )
201 ix = ix + incx
202 iy = iy + incy
203 140 CONTINUE
204 END IF
205*
206 ELSE
207 IF( incx.EQ.1 .AND. incy.EQ.1 ) THEN
208 DO 150 i = 1, n
209 y( i ) = alpha * x( i ) + beta * y( i )
210 150 CONTINUE
211 ELSE
212 ix = 1
213 iy = 1
214 DO 160 i = 1, n
215 y( iy ) = alpha * x( ix ) + beta * y( iy )
216 ix = ix + incx
217 iy = iy + incy
218 160 CONTINUE
219 END IF
220 END IF
221 END IF
222 END IF
223*
224 RETURN
225*
226* End of PBDVECADD
227*
lsame
logical function lsame(ca, cb)
Definition tools.f:1724
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