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double precision function dsum(n,dx,incx)
c
c takes the sum of the values.
c jack dongarra, linpack, 3/11/78.
c modified 3/93 to return if incx .le. 0.
c modified 12/3/93, array(1) declarations changed to array(*)
c modified 11/4/03, dasum->dsum conversion
c
double precision dx(*),dtemp
integer i,incx,m,mp1,n,nincx
c
dsum = 0.0d0
dtemp = 0.0d0
if( n.le.0 .or. incx.le.0 )return
if(incx.eq.1)go to 20
c
c code for increment not equal to 1
c
nincx = n*incx
do 10 i = 1,nincx,incx
dtemp = dtemp + dx(i)
10 continue
dsum = dtemp
return
c
c code for increment equal to 1
c
c
c clean-up loop
c
20 m = mod(n,6)
if( m .eq. 0 ) go to 40
do 30 i = 1,m
dtemp = dtemp + dx(i)
30 continue
if( n .lt. 6 ) go to 60
40 mp1 = m + 1
do 50 i = mp1,n,6
dtemp = dtemp + dx(i) + dx(i + 1) + dx(i + 2)
* + dx(i + 3) + dx(i + 4) + dx(i + 5)
50 continue
60 dsum = dtemp
return
end
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