LAPACK 3.11.0 LAPACK: Linear Algebra PACKage
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◆ sdsdot()

 real function sdsdot ( integer N, real SB, real, dimension(*) SX, integer INCX, real, dimension(*) SY, integer INCY )

SDSDOT

Purpose:
```   Compute the inner product of two vectors with extended
precision accumulation.

Returns S.P. result with dot product accumulated in D.P.
SDSDOT = SB + sum for I = 0 to N-1 of SX(LX+I*INCX)*SY(LY+I*INCY),
where LX = 1 if INCX .GE. 0, else LX = 1+(1-N)*INCX, and LY is
defined in a similar way using INCY.```
Parameters
 [in] N ``` N is INTEGER number of elements in input vector(s)``` [in] SB ``` SB is REAL single precision scalar to be added to inner product``` [in] SX ``` SX is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) single precision vector with N elements``` [in] INCX ``` INCX is INTEGER storage spacing between elements of SX``` [in] SY ``` SY is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) single precision vector with N elements``` [in] INCY ``` INCY is INTEGER storage spacing between elements of SY```
Further Details:
```    REFERENCES

C. L. Lawson, R. J. Hanson, D. R. Kincaid and F. T.
Krogh, Basic linear algebra subprograms for Fortran
usage, Algorithm No. 539, Transactions on Mathematical
Software 5, 3 (September 1979), pp. 308-323.

REVISION HISTORY  (YYMMDD)

791001  DATE WRITTEN
890531  Changed all specific intrinsics to generic.  (WRB)
890831  Modified array declarations.  (WRB)
890831  REVISION DATE from Version 3.2
891214  Prologue converted to Version 4.0 format.  (BAB)
920310  Corrected definition of LX in DESCRIPTION.  (WRB)
920501  Reformatted the REFERENCES section.  (WRB)
070118  Reformat to LAPACK coding style```

Definition at line 112 of file sdsdot.f.

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*
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
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