LAPACK 3.12.0 LAPACK: Linear Algebra PACKage
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sdsdot.f
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1*> \brief \b SDSDOT
2*
3* =========== DOCUMENTATION ===========
4*
5* Online html documentation available at
6* http://www.netlib.org/lapack/explore-html/
7*
8* Definition:
9* ===========
10*
11* REAL FUNCTION SDSDOT(N,SB,SX,INCX,SY,INCY)
12*
13* .. Scalar Arguments ..
14* REAL SB
15* INTEGER INCX,INCY,N
16* ..
17* .. Array Arguments ..
18* REAL SX(*),SY(*)
19* ..
20*
21*> \par Purpose:
22* =============
23*>
24*> \verbatim
25*>
26*> Compute the inner product of two vectors with extended
27*> precision accumulation.
28*>
29*> Returns S.P. result with dot product accumulated in D.P.
30*> SDSDOT = SB + sum for I = 0 to N-1 of SX(LX+I*INCX)*SY(LY+I*INCY),
31*> where LX = 1 if INCX .GE. 0, else LX = 1+(1-N)*INCX, and LY is
32*> defined in a similar way using INCY.
33*> \endverbatim
34*
35* Arguments:
36* ==========
37*
38*> \param[in] N
39*> \verbatim
40*> N is INTEGER
41*> number of elements in input vector(s)
42*> \endverbatim
43*>
44*> \param[in] SB
45*> \verbatim
46*> SB is REAL
47*> single precision scalar to be added to inner product
48*> \endverbatim
49*>
50*> \param[in] SX
51*> \verbatim
52*> SX is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
53*> single precision vector with N elements
54*> \endverbatim
55*>
56*> \param[in] INCX
57*> \verbatim
58*> INCX is INTEGER
59*> storage spacing between elements of SX
60*> \endverbatim
61*>
62*> \param[in] SY
63*> \verbatim
64*> SY is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) )
65*> single precision vector with N elements
66*> \endverbatim
67*>
68*> \param[in] INCY
69*> \verbatim
70*> INCY is INTEGER
71*> storage spacing between elements of SY
72*> \endverbatim
73*
74* Authors:
75* ========
76*
77*> \author Lawson, C. L., (JPL), Hanson, R. J., (SNLA),
78*> \author Kincaid, D. R., (U. of Texas), Krogh, F. T., (JPL)
79*
80*> \author Univ. of Tennessee
81*> \author Univ. of California Berkeley
82*> \author Univ. of Colorado Denver
83*> \author NAG Ltd.
84*
85*> \ingroup dot
86*
87*> \par Further Details:
88* =====================
89*>
90*> \verbatim
91*>
92*> REFERENCES
93*>
94*> C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T.
95*> Krogh, Basic linear algebra subprograms for Fortran
96*> usage, Algorithm No. 539, Transactions on Mathematical
97*> Software 5, 3 (September 1979), pp. 308-323.
98*>
99*> REVISION HISTORY (YYMMDD)
100*>
101*> 791001 DATE WRITTEN
102*> 890531 Changed all specific intrinsics to generic. (WRB)
103*> 890831 Modified array declarations. (WRB)
104*> 890831 REVISION DATE from Version 3.2
105*> 891214 Prologue converted to Version 4.0 format. (BAB)
106*> 920310 Corrected definition of LX in DESCRIPTION. (WRB)
107*> 920501 Reformatted the REFERENCES section. (WRB)
108*> 070118 Reformat to LAPACK coding style
109*> \endverbatim
110*>
111* =====================================================================
112 REAL function sdsdot(n,sb,sx,incx,sy,incy)
113*
114* -- Reference BLAS level1 routine --
115* -- Reference BLAS is a software package provided by Univ. of Tennessee, --
116* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
117*
118* .. Scalar Arguments ..
119 REAL sb
120 INTEGER incx,incy,n
121* ..
122* .. Array Arguments ..
123 REAL sx(*),sy(*)
124* .. Local Scalars ..
125 DOUBLE PRECISION dsdot
126 INTEGER i,kx,ky,ns
127* ..
128* .. Intrinsic Functions ..
129 INTRINSIC dble
130* ..
131 dsdot = sb
132 IF (n.LE.0) THEN
133 sdsdot = real(dsdot)
134 RETURN
135 END IF
136 IF (incx.EQ.incy .AND. incx.GT.0) THEN
137*
138* Code for equal and positive increments.
139*
140 ns = n*incx
141 DO i = 1,ns,incx
142 dsdot = dsdot + dble(sx(i))*dble(sy(i))
143 END DO
144 ELSE
145*
146* Code for unequal or nonpositive increments.
147*
148 kx = 1
149 ky = 1
150 IF (incx.LT.0) kx = 1 + (1-n)*incx
151 IF (incy.LT.0) ky = 1 + (1-n)*incy
152 DO i = 1,n
153 dsdot = dsdot + dble(sx(kx))*dble(sy(ky))
154 kx = kx + incx
155 ky = ky + incy
156 END DO
157 END IF
158 sdsdot = real(dsdot)
159 RETURN
160*
161* End of SDSDOT
162*
163 END
double precision function dsdot(n, sx, incx, sy, incy)
DSDOT
Definition dsdot.f:119
real function sdsdot(n, sb, sx, incx, sy, incy)
SDSDOT
Definition sdsdot.f:113