LAPACK 3.12.0 LAPACK: Linear Algebra PACKage
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## ◆ sdot()

 real function sdot ( integer n, real, dimension(*) sx, integer incx, real, dimension(*) sy, integer incy )

SDOT

Purpose:
```    SDOT forms the dot product of two vectors.
uses unrolled loops for increments equal to one.```
Parameters
 [in] N ``` N is INTEGER number of elements in input vector(s)``` [in] SX ` SX is REAL array, dimension ( 1 + ( N - 1 )*abs( INCX ) )` [in] INCX ``` INCX is INTEGER storage spacing between elements of SX``` [in] SY ` SY is REAL array, dimension ( 1 + ( N - 1 )*abs( INCY ) )` [in] INCY ``` INCY is INTEGER storage spacing between elements of SY```
Further Details:
```     jack dongarra, linpack, 3/11/78.
modified 12/3/93, array(1) declarations changed to array(*)```

Definition at line 81 of file sdot.f.

82*
83* -- Reference BLAS level1 routine --
84* -- Reference BLAS is a software package provided by Univ. of Tennessee, --
85* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
86*
87* .. Scalar Arguments ..
88 INTEGER INCX,INCY,N
89* ..
90* .. Array Arguments ..
91 REAL SX(*),SY(*)
92* ..
93*
94* =====================================================================
95*
96* .. Local Scalars ..
97 REAL STEMP
98 INTEGER I,IX,IY,M,MP1
99* ..
100* .. Intrinsic Functions ..
101 INTRINSIC mod
102* ..
103 stemp = 0.0e0
104 sdot = 0.0e0
105 IF (n.LE.0) RETURN
106 IF (incx.EQ.1 .AND. incy.EQ.1) THEN
107*
108* code for both increments equal to 1
109*
110*
111* clean-up loop
112*
113 m = mod(n,5)
114 IF (m.NE.0) THEN
115 DO i = 1,m
116 stemp = stemp + sx(i)*sy(i)
117 END DO
118 IF (n.LT.5) THEN
119 sdot=stemp
120 RETURN
121 END IF
122 END IF
123 mp1 = m + 1
124 DO i = mp1,n,5
125 stemp = stemp + sx(i)*sy(i) + sx(i+1)*sy(i+1) +
126 \$ sx(i+2)*sy(i+2) + sx(i+3)*sy(i+3) + sx(i+4)*sy(i+4)
127 END DO
128 ELSE
129*
130* code for unequal increments or equal increments
131* not equal to 1
132*
133 ix = 1
134 iy = 1
135 IF (incx.LT.0) ix = (-n+1)*incx + 1
136 IF (incy.LT.0) iy = (-n+1)*incy + 1
137 DO i = 1,n
138 stemp = stemp + sx(ix)*sy(iy)
139 ix = ix + incx
140 iy = iy + incy
141 END DO
142 END IF
143 sdot = stemp
144 RETURN
145*
146* End of SDOT
147*
real function sdot(n, sx, incx, sy, incy)
SDOT
Definition sdot.f:82
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