 LAPACK  3.10.0 LAPACK: Linear Algebra PACKage

## ◆ 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 = 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 = 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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